Project Euler 41~45

Problem 41:

We shall say that an n-digit number is pandigital if it makes use of all the digits 1 to
n exactly once. For example, 2143 is a 4-digit pandigital and is also prime.

What is the largest n-digit pandigital prime that exists?

#!/usr/bin/python3
from math import *
ans=0
v=[0 for i in range(10)]
def prime(x):
for i in range(2,int(sqrt(x))+1):
if x%i==0:
return 0
return 1
def dfs(l,x):
if l==7:
if prime(x):
global ans
if x>ans:
ans=x
for i in range(1,8):
if not v[i]:
v[i]=1
dfs(l+1,x*10+i)
v[i]=0
dfs(0,0)
print(ans)

Answer:7652413

Problem 42:

The nth term of the sequence of triangle numbers is given by,
tn = ½n(n+1); so the first ten triangle numbers are:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 =
t10. If the word value is a triangle number then we shall call the word a triangle word.

Using words.txt (right click and 'Save Link/Target As...'), a 16K text file containing nearly two-thousand common English words, how many are triangle words?

#!/usr/bin/python3
name=["A","ABILITY","ABLE","ABOUT","ABOVE","ABSENCE","ABSOLUTELY","ACADEMIC","ACCEPT","ACCESS","ACCIDENT","ACCOMPANY","ACCORDING","ACCOUNT","ACHIEVE","ACHIEVEMENT","ACID","ACQUIRE","ACROSS","ACT","ACTION","ACTIVE","ACTIVITY","ACTUAL","ACTUALLY","ADD","ADDITION","ADDITIONAL","ADDRESS","ADMINISTRATION","ADMIT","ADOPT","ADULT","ADVANCE","ADVANTAGE","ADVICE","ADVISE","AFFAIR","AFFECT","AFFORD","AFRAID","AFTER","AFTERNOON","AFTERWARDS","AGAIN","AGAINST","AGE","AGENCY","AGENT","AGO","AGREE","AGREEMENT","AHEAD","AID","AIM","AIR","AIRCRAFT","ALL","ALLOW","ALMOST","ALONE","ALONG","ALREADY","ALRIGHT","ALSO","ALTERNATIVE","ALTHOUGH","ALWAYS","AMONG","AMONGST","AMOUNT","AN","ANALYSIS","ANCIENT","AND","ANIMAL","ANNOUNCE","ANNUAL","ANOTHER","ANSWER","ANY","ANYBODY","ANYONE","ANYTHING","ANYWAY","APART","APPARENT","APPARENTLY","APPEAL","APPEAR","APPEARANCE","APPLICATION","APPLY","APPOINT","APPOINTMENT","APPROACH","APPROPRIATE","APPROVE","AREA","ARGUE","ARGUMENT","ARISE","ARM","ARMY","AROUND","ARRANGE","ARRANGEMENT","ARRIVE","ART","ARTICLE","ARTIST","AS","ASK","ASPECT","ASSEMBLY","ASSESS","ASSESSMENT","ASSET","ASSOCIATE","ASSOCIATION","ASSUME","ASSUMPTION","AT","ATMOSPHERE","ATTACH","ATTACK","ATTEMPT","ATTEND","ATTENTION","ATTITUDE","ATTRACT","ATTRACTIVE","AUDIENCE","AUTHOR","AUTHORITY","AVAILABLE","AVERAGE","AVOID","AWARD","AWARE","AWAY","AYE","BABY","BACK","BACKGROUND","BAD","BAG","BALANCE","BALL","BAND","BANK","BAR","BASE","BASIC","BASIS","BATTLE","BE","BEAR","BEAT","BEAUTIFUL","BECAUSE","BECOME","BED","BEDROOM","BEFORE","BEGIN","BEGINNING","BEHAVIOUR","BEHIND","BELIEF","BELIEVE","BELONG","BELOW","BENEATH","BENEFIT","BESIDE","BEST","BETTER","BETWEEN","BEYOND","BIG","BILL","BIND","BIRD","BIRTH","BIT","BLACK","BLOCK","BLOOD","BLOODY","BLOW","BLUE","BOARD","BOAT","BODY","BONE","BOOK","BORDER","BOTH","BOTTLE","BOTTOM","BOX","BOY","BRAIN","BRANCH","BREAK","BREATH","BRIDGE","BRIEF","BRIGHT","BRING","BROAD","BROTHER","BUDGET","BUILD","BUILDING","BURN","BUS","BUSINESS","BUSY","BUT","BUY","BY","CABINET","CALL","CAMPAIGN","CAN","CANDIDATE","CAPABLE","CAPACITY","CAPITAL","CAR","CARD","CARE","CAREER","CAREFUL","CAREFULLY","CARRY","CASE","CASH","CAT","CATCH","CATEGORY","CAUSE","CELL","CENTRAL","CENTRE","CENTURY","CERTAIN","CERTAINLY","CHAIN","CHAIR","CHAIRMAN","CHALLENGE","CHANCE","CHANGE","CHANNEL","CHAPTER","CHARACTER","CHARACTERISTIC","CHARGE","CHEAP","CHECK","CHEMICAL","CHIEF","CHILD","CHOICE","CHOOSE","CHURCH","CIRCLE","CIRCUMSTANCE","CITIZEN","CITY","CIVIL","CLAIM","CLASS","CLEAN","CLEAR","CLEARLY","CLIENT","CLIMB","CLOSE","CLOSELY","CLOTHES","CLUB","COAL","CODE","COFFEE","COLD","COLLEAGUE","COLLECT","COLLECTION","COLLEGE","COLOUR","COMBINATION","COMBINE","COME","COMMENT","COMMERCIAL","COMMISSION","COMMIT","COMMITMENT","COMMITTEE","COMMON","COMMUNICATION","COMMUNITY","COMPANY","COMPARE","COMPARISON","COMPETITION","COMPLETE","COMPLETELY","COMPLEX","COMPONENT","COMPUTER","CONCENTRATE","CONCENTRATION","CONCEPT","CONCERN","CONCERNED","CONCLUDE","CONCLUSION","CONDITION","CONDUCT","CONFERENCE","CONFIDENCE","CONFIRM","CONFLICT","CONGRESS","CONNECT","CONNECTION","CONSEQUENCE","CONSERVATIVE","CONSIDER","CONSIDERABLE","CONSIDERATION","CONSIST","CONSTANT","CONSTRUCTION","CONSUMER","CONTACT","CONTAIN","CONTENT","CONTEXT","CONTINUE","CONTRACT","CONTRAST","CONTRIBUTE","CONTRIBUTION","CONTROL","CONVENTION","CONVERSATION","COPY","CORNER","CORPORATE","CORRECT","COS","COST","COULD","COUNCIL","COUNT","COUNTRY","COUNTY","COUPLE","COURSE","COURT","COVER","CREATE","CREATION","CREDIT","CRIME","CRIMINAL","CRISIS","CRITERION","CRITICAL","CRITICISM","CROSS","CROWD","CRY","CULTURAL","CULTURE","CUP","CURRENT","CURRENTLY","CURRICULUM","CUSTOMER","CUT","DAMAGE","DANGER","DANGEROUS","DARK","DATA","DATE","DAUGHTER","DAY","DEAD","DEAL","DEATH","DEBATE","DEBT","DECADE","DECIDE","DECISION","DECLARE","DEEP","DEFENCE","DEFENDANT","DEFINE","DEFINITION","DEGREE","DELIVER","DEMAND","DEMOCRATIC","DEMONSTRATE","DENY","DEPARTMENT","DEPEND","DEPUTY","DERIVE","DESCRIBE","DESCRIPTION","DESIGN","DESIRE","DESK","DESPITE","DESTROY","DETAIL","DETAILED","DETERMINE","DEVELOP","DEVELOPMENT","DEVICE","DIE","DIFFERENCE","DIFFERENT","DIFFICULT","DIFFICULTY","DINNER","DIRECT","DIRECTION","DIRECTLY","DIRECTOR","DISAPPEAR","DISCIPLINE","DISCOVER","DISCUSS","DISCUSSION","DISEASE","DISPLAY","DISTANCE","DISTINCTION","DISTRIBUTION","DISTRICT","DIVIDE","DIVISION","DO","DOCTOR","DOCUMENT","DOG","DOMESTIC","DOOR","DOUBLE","DOUBT","DOWN","DRAW","DRAWING","DREAM","DRESS","DRINK","DRIVE","DRIVER","DROP","DRUG","DRY","DUE","DURING","DUTY","EACH","EAR","EARLY","EARN","EARTH","EASILY","EAST","EASY","EAT","ECONOMIC","ECONOMY","EDGE","EDITOR","EDUCATION","EDUCATIONAL","EFFECT","EFFECTIVE","EFFECTIVELY","EFFORT","EGG","EITHER","ELDERLY","ELECTION","ELEMENT","ELSE","ELSEWHERE","EMERGE","EMPHASIS","EMPLOY","EMPLOYEE","EMPLOYER","EMPLOYMENT","EMPTY","ENABLE","ENCOURAGE","END","ENEMY","ENERGY","ENGINE","ENGINEERING","ENJOY","ENOUGH","ENSURE","ENTER","ENTERPRISE","ENTIRE","ENTIRELY","ENTITLE","ENTRY","ENVIRONMENT","ENVIRONMENTAL","EQUAL","EQUALLY","EQUIPMENT","ERROR","ESCAPE","ESPECIALLY","ESSENTIAL","ESTABLISH","ESTABLISHMENT","ESTATE","ESTIMATE","EVEN","EVENING","EVENT","EVENTUALLY","EVER","EVERY","EVERYBODY","EVERYONE","EVERYTHING","EVIDENCE","EXACTLY","EXAMINATION","EXAMINE","EXAMPLE","EXCELLENT","EXCEPT","EXCHANGE","EXECUTIVE","EXERCISE","EXHIBITION","EXIST","EXISTENCE","EXISTING","EXPECT","EXPECTATION","EXPENDITURE","EXPENSE","EXPENSIVE","EXPERIENCE","EXPERIMENT","EXPERT","EXPLAIN","EXPLANATION","EXPLORE","EXPRESS","EXPRESSION","EXTEND","EXTENT","EXTERNAL","EXTRA","EXTREMELY","EYE","FACE","FACILITY","FACT","FACTOR","FACTORY","FAIL","FAILURE","FAIR","FAIRLY","FAITH","FALL","FAMILIAR","FAMILY","FAMOUS","FAR","FARM","FARMER","FASHION","FAST","FATHER","FAVOUR","FEAR","FEATURE","FEE","FEEL","FEELING","FEMALE","FEW","FIELD","FIGHT","FIGURE","FILE","FILL","FILM","FINAL","FINALLY","FINANCE","FINANCIAL","FIND","FINDING","FINE","FINGER","FINISH","FIRE","FIRM","FIRST","FISH","FIT","FIX","FLAT","FLIGHT","FLOOR","FLOW","FLOWER","FLY","FOCUS","FOLLOW","FOLLOWING","FOOD","FOOT","FOOTBALL","FOR","FORCE","FOREIGN","FOREST","FORGET","FORM","FORMAL","FORMER","FORWARD","FOUNDATION","FREE","FREEDOM","FREQUENTLY","FRESH","FRIEND","FROM","FRONT","FRUIT","FUEL","FULL","FULLY","FUNCTION","FUND","FUNNY","FURTHER","FUTURE","GAIN","GAME","GARDEN","GAS","GATE","GATHER","GENERAL","GENERALLY","GENERATE","GENERATION","GENTLEMAN","GET","GIRL","GIVE","GLASS","GO","GOAL","GOD","GOLD","GOOD","GOVERNMENT","GRANT","GREAT","GREEN","GREY","GROUND","GROUP","GROW","GROWING","GROWTH","GUEST","GUIDE","GUN","HAIR","HALF","HALL","HAND","HANDLE","HANG","HAPPEN","HAPPY","HARD","HARDLY","HATE","HAVE","HE","HEAD","HEALTH","HEAR","HEART","HEAT","HEAVY","HELL","HELP","HENCE","HER","HERE","HERSELF","HIDE","HIGH","HIGHLY","HILL","HIM","HIMSELF","HIS","HISTORICAL","HISTORY","HIT","HOLD","HOLE","HOLIDAY","HOME","HOPE","HORSE","HOSPITAL","HOT","HOTEL","HOUR","HOUSE","HOUSEHOLD","HOUSING","HOW","HOWEVER","HUGE","HUMAN","HURT","HUSBAND","I","IDEA","IDENTIFY","IF","IGNORE","ILLUSTRATE","IMAGE","IMAGINE","IMMEDIATE","IMMEDIATELY","IMPACT","IMPLICATION","IMPLY","IMPORTANCE","IMPORTANT","IMPOSE","IMPOSSIBLE","IMPRESSION","IMPROVE","IMPROVEMENT","IN","INCIDENT","INCLUDE","INCLUDING","INCOME","INCREASE","INCREASED","INCREASINGLY","INDEED","INDEPENDENT","INDEX","INDICATE","INDIVIDUAL","INDUSTRIAL","INDUSTRY","INFLUENCE","INFORM","INFORMATION","INITIAL","INITIATIVE","INJURY","INSIDE","INSIST","INSTANCE","INSTEAD","INSTITUTE","INSTITUTION","INSTRUCTION","INSTRUMENT","INSURANCE","INTEND","INTENTION","INTEREST","INTERESTED","INTERESTING","INTERNAL","INTERNATIONAL","INTERPRETATION","INTERVIEW","INTO","INTRODUCE","INTRODUCTION","INVESTIGATE","INVESTIGATION","INVESTMENT","INVITE","INVOLVE","IRON","IS","ISLAND","ISSUE","IT","ITEM","ITS","ITSELF","JOB","JOIN","JOINT","JOURNEY","JUDGE","JUMP","JUST","JUSTICE","KEEP","KEY","KID","KILL","KIND","KING","KITCHEN","KNEE","KNOW","KNOWLEDGE","LABOUR","LACK","LADY","LAND","LANGUAGE","LARGE","LARGELY","LAST","LATE","LATER","LATTER","LAUGH","LAUNCH","LAW","LAWYER","LAY","LEAD","LEADER","LEADERSHIP","LEADING","LEAF","LEAGUE","LEAN","LEARN","LEAST","LEAVE","LEFT","LEG","LEGAL","LEGISLATION","LENGTH","LESS","LET","LETTER","LEVEL","LIABILITY","LIBERAL","LIBRARY","LIE","LIFE","LIFT","LIGHT","LIKE","LIKELY","LIMIT","LIMITED","LINE","LINK","LIP","LIST","LISTEN","LITERATURE","LITTLE","LIVE","LIVING","LOAN","LOCAL","LOCATION","LONG","LOOK","LORD","LOSE","LOSS","LOT","LOVE","LOVELY","LOW","LUNCH","MACHINE","MAGAZINE","MAIN","MAINLY","MAINTAIN","MAJOR","MAJORITY","MAKE","MALE","MAN","MANAGE","MANAGEMENT","MANAGER","MANNER","MANY","MAP","MARK","MARKET","MARRIAGE","MARRIED","MARRY","MASS","MASTER","MATCH","MATERIAL","MATTER","MAY","MAYBE","ME","MEAL","MEAN","MEANING","MEANS","MEANWHILE","MEASURE","MECHANISM","MEDIA","MEDICAL","MEET","MEETING","MEMBER","MEMBERSHIP","MEMORY","MENTAL","MENTION","MERELY","MESSAGE","METAL","METHOD","MIDDLE","MIGHT","MILE","MILITARY","MILK","MIND","MINE","MINISTER","MINISTRY","MINUTE","MISS","MISTAKE","MODEL","MODERN","MODULE","MOMENT","MONEY","MONTH","MORE","MORNING","MOST","MOTHER","MOTION","MOTOR","MOUNTAIN","MOUTH","MOVE","MOVEMENT","MUCH","MURDER","MUSEUM","MUSIC","MUST","MY","MYSELF","NAME","NARROW","NATION","NATIONAL","NATURAL","NATURE","NEAR","NEARLY","NECESSARILY","NECESSARY","NECK","NEED","NEGOTIATION","NEIGHBOUR","NEITHER","NETWORK","NEVER","NEVERTHELESS","NEW","NEWS","NEWSPAPER","NEXT","NICE","NIGHT","NO","NOBODY","NOD","NOISE","NONE","NOR","NORMAL","NORMALLY","NORTH","NORTHERN","NOSE","NOT","NOTE","NOTHING","NOTICE","NOTION","NOW","NUCLEAR","NUMBER","NURSE","OBJECT","OBJECTIVE","OBSERVATION","OBSERVE","OBTAIN","OBVIOUS","OBVIOUSLY","OCCASION","OCCUR","ODD","OF","OFF","OFFENCE","OFFER","OFFICE","OFFICER","OFFICIAL","OFTEN","OIL","OKAY","OLD","ON","ONCE","ONE","ONLY","ONTO","OPEN","OPERATE","OPERATION","OPINION","OPPORTUNITY","OPPOSITION","OPTION","OR","ORDER","ORDINARY","ORGANISATION","ORGANISE","ORGANIZATION","ORIGIN","ORIGINAL","OTHER","OTHERWISE","OUGHT","OUR","OURSELVES","OUT","OUTCOME","OUTPUT","OUTSIDE","OVER","OVERALL","OWN","OWNER","PACKAGE","PAGE","PAIN","PAINT","PAINTING","PAIR","PANEL","PAPER","PARENT","PARK","PARLIAMENT","PART","PARTICULAR","PARTICULARLY","PARTLY","PARTNER","PARTY","PASS","PASSAGE","PAST","PATH","PATIENT","PATTERN","PAY","PAYMENT","PEACE","PENSION","PEOPLE","PER","PERCENT","PERFECT","PERFORM","PERFORMANCE","PERHAPS","PERIOD","PERMANENT","PERSON","PERSONAL","PERSUADE","PHASE","PHONE","PHOTOGRAPH","PHYSICAL","PICK","PICTURE","PIECE","PLACE","PLAN","PLANNING","PLANT","PLASTIC","PLATE","PLAY","PLAYER","PLEASE","PLEASURE","PLENTY","PLUS","POCKET","POINT","POLICE","POLICY","POLITICAL","POLITICS","POOL","POOR","POPULAR","POPULATION","POSITION","POSITIVE","POSSIBILITY","POSSIBLE","POSSIBLY","POST","POTENTIAL","POUND","POWER","POWERFUL","PRACTICAL","PRACTICE","PREFER","PREPARE","PRESENCE","PRESENT","PRESIDENT","PRESS","PRESSURE","PRETTY","PREVENT","PREVIOUS","PREVIOUSLY","PRICE","PRIMARY","PRIME","PRINCIPLE","PRIORITY","PRISON","PRISONER","PRIVATE","PROBABLY","PROBLEM","PROCEDURE","PROCESS","PRODUCE","PRODUCT","PRODUCTION","PROFESSIONAL","PROFIT","PROGRAM","PROGRAMME","PROGRESS","PROJECT","PROMISE","PROMOTE","PROPER","PROPERLY","PROPERTY","PROPORTION","PROPOSE","PROPOSAL","PROSPECT","PROTECT","PROTECTION","PROVE","PROVIDE","PROVIDED","PROVISION","PUB","PUBLIC","PUBLICATION","PUBLISH","PULL","PUPIL","PURPOSE","PUSH","PUT","QUALITY","QUARTER","QUESTION","QUICK","QUICKLY","QUIET","QUITE","RACE","RADIO","RAILWAY","RAIN","RAISE","RANGE","RAPIDLY","RARE","RATE","RATHER","REACH","REACTION","READ","READER","READING","READY","REAL","REALISE","REALITY","REALIZE","REALLY","REASON","REASONABLE","RECALL","RECEIVE","RECENT","RECENTLY","RECOGNISE","RECOGNITION","RECOGNIZE","RECOMMEND","RECORD","RECOVER","RED","REDUCE","REDUCTION","REFER","REFERENCE","REFLECT","REFORM","REFUSE","REGARD","REGION","REGIONAL","REGULAR","REGULATION","REJECT","RELATE","RELATION","RELATIONSHIP","RELATIVE","RELATIVELY","RELEASE","RELEVANT","RELIEF","RELIGION","RELIGIOUS","RELY","REMAIN","REMEMBER","REMIND","REMOVE","REPEAT","REPLACE","REPLY","REPORT","REPRESENT","REPRESENTATION","REPRESENTATIVE","REQUEST","REQUIRE","REQUIREMENT","RESEARCH","RESOURCE","RESPECT","RESPOND","RESPONSE","RESPONSIBILITY","RESPONSIBLE","REST","RESTAURANT","RESULT","RETAIN","RETURN","REVEAL","REVENUE","REVIEW","REVOLUTION","RICH","RIDE","RIGHT","RING","RISE","RISK","RIVER","ROAD","ROCK","ROLE","ROLL","ROOF","ROOM","ROUND","ROUTE","ROW","ROYAL","RULE","RUN","RURAL","SAFE","SAFETY","SALE","SAME","SAMPLE","SATISFY","SAVE","SAY","SCALE","SCENE","SCHEME","SCHOOL","SCIENCE","SCIENTIFIC","SCIENTIST","SCORE","SCREEN","SEA","SEARCH","SEASON","SEAT","SECOND","SECONDARY","SECRETARY","SECTION","SECTOR","SECURE","SECURITY","SEE","SEEK","SEEM","SELECT","SELECTION","SELL","SEND","SENIOR","SENSE","SENTENCE","SEPARATE","SEQUENCE","SERIES","SERIOUS","SERIOUSLY","SERVANT","SERVE","SERVICE","SESSION","SET","SETTLE","SETTLEMENT","SEVERAL","SEVERE","SEX","SEXUAL","SHAKE","SHALL","SHAPE","SHARE","SHE","SHEET","SHIP","SHOE","SHOOT","SHOP","SHORT","SHOT","SHOULD","SHOULDER","SHOUT","SHOW","SHUT","SIDE","SIGHT","SIGN","SIGNAL","SIGNIFICANCE","SIGNIFICANT","SILENCE","SIMILAR","SIMPLE","SIMPLY","SINCE","SING","SINGLE","SIR","SISTER","SIT","SITE","SITUATION","SIZE","SKILL","SKIN","SKY","SLEEP","SLIGHTLY","SLIP","SLOW","SLOWLY","SMALL","SMILE","SO","SOCIAL","SOCIETY","SOFT","SOFTWARE","SOIL","SOLDIER","SOLICITOR","SOLUTION","SOME","SOMEBODY","SOMEONE","SOMETHING","SOMETIMES","SOMEWHAT","SOMEWHERE","SON","SONG","SOON","SORRY","SORT","SOUND","SOURCE","SOUTH","SOUTHERN","SPACE","SPEAK","SPEAKER","SPECIAL","SPECIES","SPECIFIC","SPEECH","SPEED","SPEND","SPIRIT","SPORT","SPOT","SPREAD","SPRING","STAFF","STAGE","STAND","STANDARD","STAR","START","STATE","STATEMENT","STATION","STATUS","STAY","STEAL","STEP","STICK","STILL","STOCK","STONE","STOP","STORE","STORY","STRAIGHT","STRANGE","STRATEGY","STREET","STRENGTH","STRIKE","STRONG","STRONGLY","STRUCTURE","STUDENT","STUDIO","STUDY","STUFF","STYLE","SUBJECT","SUBSTANTIAL","SUCCEED","SUCCESS","SUCCESSFUL","SUCH","SUDDENLY","SUFFER","SUFFICIENT","SUGGEST","SUGGESTION","SUITABLE","SUM","SUMMER","SUN","SUPPLY","SUPPORT","SUPPOSE","SURE","SURELY","SURFACE","SURPRISE","SURROUND","SURVEY","SURVIVE","SWITCH","SYSTEM","TABLE","TAKE","TALK","TALL","TAPE","TARGET","TASK","TAX","TEA","TEACH","TEACHER","TEACHING","TEAM","TEAR","TECHNICAL","TECHNIQUE","TECHNOLOGY","TELEPHONE","TELEVISION","TELL","TEMPERATURE","TEND","TERM","TERMS","TERRIBLE","TEST","TEXT","THAN","THANK","THANKS","THAT","THE","THEATRE","THEIR","THEM","THEME","THEMSELVES","THEN","THEORY","THERE","THEREFORE","THESE","THEY","THIN","THING","THINK","THIS","THOSE","THOUGH","THOUGHT","THREAT","THREATEN","THROUGH","THROUGHOUT","THROW","THUS","TICKET","TIME","TINY","TITLE","TO","TODAY","TOGETHER","TOMORROW","TONE","TONIGHT","TOO","TOOL","TOOTH","TOP","TOTAL","TOTALLY","TOUCH","TOUR","TOWARDS","TOWN","TRACK","TRADE","TRADITION","TRADITIONAL","TRAFFIC","TRAIN","TRAINING","TRANSFER","TRANSPORT","TRAVEL","TREAT","TREATMENT","TREATY","TREE","TREND","TRIAL","TRIP","TROOP","TROUBLE","TRUE","TRUST","TRUTH","TRY","TURN","TWICE","TYPE","TYPICAL","UNABLE","UNDER","UNDERSTAND","UNDERSTANDING","UNDERTAKE","UNEMPLOYMENT","UNFORTUNATELY","UNION","UNIT","UNITED","UNIVERSITY","UNLESS","UNLIKELY","UNTIL","UP","UPON","UPPER","URBAN","US","USE","USED","USEFUL","USER","USUAL","USUALLY","VALUE","VARIATION","VARIETY","VARIOUS","VARY","VAST","VEHICLE","VERSION","VERY","VIA","VICTIM","VICTORY","VIDEO","VIEW","VILLAGE","VIOLENCE","VISION","VISIT","VISITOR","VITAL","VOICE","VOLUME","VOTE","WAGE","WAIT","WALK","WALL","WANT","WAR","WARM","WARN","WASH","WATCH","WATER","WAVE","WAY","WE","WEAK","WEAPON","WEAR","WEATHER","WEEK","WEEKEND","WEIGHT","WELCOME","WELFARE","WELL","WEST","WESTERN","WHAT","WHATEVER","WHEN","WHERE","WHEREAS","WHETHER","WHICH","WHILE","WHILST","WHITE","WHO","WHOLE","WHOM","WHOSE","WHY","WIDE","WIDELY","WIFE","WILD","WILL","WIN","WIND","WINDOW","WINE","WING","WINNER","WINTER","WISH","WITH","WITHDRAW","WITHIN","WITHOUT","WOMAN","WONDER","WONDERFUL","WOOD","WORD","WORK","WORKER","WORKING","WORKS","WORLD","WORRY","WORTH","WOULD","WRITE","WRITER","WRITING","WRONG","YARD","YEAH","YEAR","YES","YESTERDAY","YET","YOU","YOUNG","YOUR","YOURSELF","YOUTH"]
f=[0 for i in range(1000)]
ans=0
def key(s):
k=0
for i in range(len(s)):
k+=ord(s[i])-ord('A')+1
return k
for i in range(1,30+1):
x=i*(i+1)//2
f[x]=1
for i in name:
if f[key(i)]:
ans+=1
print(ans)

Answer:162

Problem 43:

The number, 1406357289, is a 0 to 9 pandigital number because it is made up of each of the digits 0 to 9 in some order, but it also has a rather interesting sub-string divisibility property.

Let d1 be the 1st digit, d2 be the 2nd digit, and so on. In this way, we note the following:

d2d3d4=406 is divisible by 2
d3d4d5=063 is divisible by 3
d4d5d6=635 is divisible by 5
d5d6d7=357 is divisible by 7
d6d7d8=572 is divisible by 11
d7d8d9=728 is divisible by 13
d8d9d10=289 is divisible by 17
Find the sum of all 0 to 9 pandigital numbers with this property.

#!/usr/bin/python3
ans=0
v=[0 for i in range(10)]
def dfs(l,x):
if l==10:
d=str(x)
if int(d[1]+d[2]+d[3])%2==0 and int(d[2]+d[3]+d[4])%3==0 and int(d[3]+d[4]+d[5])%5==0 and int(d[4]+d[5]+d[6])%7==0 and int(d[5]+d[6]+d[7])%11==0 and int(d[6]+d[7]+d[8])%13==0 and int(d[7]+d[8]+d[9])%17==0:
global ans
ans+=x
for i in range(10):
if l==0 and i and not v[i] or l and not v[i]:
v[i]=1
dfs(l+1,x*10+i)
v[i]=0
dfs(0,0)
print(ans)

Answer:16695334890

Problem 44:

Pentagonal numbers are generated by the formula, Pn=n(3n

1)/2. The first ten pentagonal
numbers are:

1, 5, 12, 22, 35, 51, 70, 92, 117, 145, ...
It can be seen that P4 + P7 = 22 + 70 = 92 = P8. However, their difference, 70


22 = 48, is not pentagonal.

Find the pair of pentagonal numbers, Pj and Pk, for which their sum and difference are pentagonal and D = |Pk

Pj| is minimised; what is the value of D?

#!/usr/bin/python3
from math import *
def f(x):
return x*(3*x-1)//2
def g(n):
n*=6
m=int(sqrt(n))
if m%3==2 and m*(m+1)==n:
return 1
else:
return 0
k=ans=0
while not ans:
k+=1
t=f(k)
j=k-1
while j and not ans:
s=f(j)
if g(t+s) and g(t-s):
ans=t-s
j-=1
print(ans)

Answer:5482660

Problem 45:

Triangle, pentagonal, and hexagonal numbers are generated by the following formulae:

Triangle		Tn=n(n+1)/2		1, 3, 6, 10, 15, ...
Pentagonal		Pn=n(3n 1)/2		1, 5, 12, 22, 35, ...
Hexagonal		Hn=n(2n 1)		1, 6, 15, 28, 45, ...

It can be verified that T285 = P165 = H143 = 40755.

Find the next triangle number that is also pentagonal and hexagonal.

#!/usr/bin/python3
from math import *
def t(x):
return x*(x+1)//2
def p(x):
return x*(3*x-1)//2
def h(x):
return x*(2*x-1)
def T(x):
x*=2
y=int(sqrt(x))
if y*(y+1)==x:
return 1
else:
return 0
def P(x):
x*=6
y=int(sqrt(x))
if y%3==2 and y*(y+1)==x:
return 1
else:
return 0
ind=143
while 1:
ind+=1
t=h(ind)
if T(t) and P(t):
print(t)
break

Answer:1533776805

By Charlie Pan
Apr 24,2014