训练指南（白书）习题记录

第一章

UVa11636 你好世界！

ans=floor(log(n-1))+1 显然是以2为底的

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
#include<map>
#define LL long long
#define INF 1000000000
#define eps 1e-10
#define sqr(x) (x)*(x)
#define pa pair<int,int>
#define cyc(i,x,y) for(int i=(x);i<=(y);i++)
#define cy2(i,x,y) for(int i=(x);i>=(y);i--)
using namespace std;
inline int read()
{
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();}
return x*f;
}
int main()
{
//  freopen("input.in","r",stdin);
//  freopen("output.out","w",stdout);
int x=read(),cs=0;
while(x>=0)
{
++cs;
if(x==1)printf("Case %d: 0\n",cs);else
printf("Case %d: %.0lf\n",cs,floor(log2(x-1))+1);
x=read();
}
return 0;
}

UVa11039 设计建筑物

绝对值排一遍序

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <cmath>
using namespace std;

const int MAXN = 500010;

int A[MAXN];
int n;

int cmp(int a, int b)
{
return abs(a) < abs(b);
}

void read_case()
{
scanf("%d", &n);
for(int i = 1; i <= n; i++) scanf("%d", &A[i]);
sort(A+1, A+1+n, cmp);
}

void solve()
{
read_case();
int count = 0;
int flag = 0;
for(int i = 1; i <= n; i++)
{
if(flag == 0)
{
if(A[i] > 0) flag = 1;
else flag = 2;
count++;
}
else if(flag == 1)
{
if(A[i] < 0) {flag = 2; count++;}
}
else if(flag == 2)
{
if(A[i] > 0) {flag = 1; count++;}
}
}
printf("%d\n", count);
}

int main()
{
int T;
scanf("%d", &T);
while(T--)
{
solve();
}
return 0;
}

LA3213 古老的密码

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>
#include <cstring>
#include <cmath>
#include <vector>
#include <queue>
#include <stack>
#include <algorithm>
using namespace std;

const int maxn = 1010;
const int sigma_size = 26;

char str1[maxn], str2[maxn];
int count1[sigma_size], count2[sigma_size];

void init()
{
memset(count1, 0, sizeof(count1));
memset(count2, 0, sizeof(count2));
}

int cmp(int a, int b)
{
return a > b;
}

void solve()
{
init();
for(int i = 0; str1[i]; i++) count1[str1[i]-'A']++;
for(int i = 0; str2[i]; i++) count2[str2[i]-'A']++;
sort(count1, count1+sigma_size, cmp);
sort(count2, count2+sigma_size, cmp);
for(int i = 0; i < sigma_size; i++)
{
if(count1[i] != count2[i]) { printf("NO\n"); return ;}
}
printf("YES\n");
}

int main()
{
while(~scanf("%s%s", str1, str2))
{
solve();
}
return 0;
}

LA3602 DNA序列

贪心枚举位置每次选择出现次数最多的O(mn)

#include <stdio.h>
#include <string.h>
const char X[] = {'A', 'C', 'G', 'T'};
int main()
{
int m, n, t, i, j, d, ct[4];
char dna[50][1005];
char ans[1005];
scanf("%d", &t);
while(t--)
{
d = 0;
scanf("%d%d", &m, &n);
i = 0;
while(i < m)
scanf("%s", dna[i++]);
//统计每列各种字符数
for(j = 0; j < n; ++j)
{
memset(ct, 0, sizeof(ct));
for(i = 0; i < m; ++i)
{
if('A' == dna[i][j]) ++ct[0];
else if('C' == dna[i][j]) ++ct[1];
else if('G' == dna[i][j]) ++ct[2];
else ++ct[3];
}
//找出每列出现最多的字符
int max = -1;
char ch = 255;
for(i = 0; i < 4; ++i)
{
if(ct[i] > max)
{
max = ct[i];
ch = X[i];
}
else if(ct[i] == max)
if(X[i] < ch)
ch = X[i];
}
//计算距离
for(i = 0; i < m; ++i)
if(dna[i][j] != ch) ++d;
ans[j] = ch;
}
ans
= '\0';
printf("%s\n%d\n", ans, d);
}
return 0;
}

UVa10970 大块巧克力

很奇怪的一个题 ans=m*n-1 ？？？

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
#include<map>
#define LL long long
#define INF 1000000000
#define eps 1e-10
#define sqr(x) (x)*(x)
#define pa pair<int,int>
#define cyc(i,x,y) for(int i=(x);i<=(y);i++)
#define cy2(i,x,y) for(int i=(x);i>=(y);i--)
using namespace std;
inline int read()
{
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();}
return x*f;
}
int n,m;
int main()
{
//  freopen("input.in","r",stdin);
//  freopen("output.out","w",stdout);
while(~scanf("%d%d",&n,&m))printf("%d\n",n*m-1);
return 0;
}

UVa10382 喷水装置

贪心 只要能覆盖底边就能覆盖整个长条 转化成用最少的区间覆盖0-L

自己写的总是wa

#include<iostream>
#include<cmath>
#include<cstdio>
#include<algorithm>
#define MAXN 10005
using namespace std;
int n,nIndex;
double l, w;

struct Node{
double left;
double right;
friend bool operator < (const Node&a,const Node&b){
return a.left < b.left;
}
}arr[MAXN];

int main(){
double p,r;
while(scanf("%d%lf%lf",&n,&l,&w)!=EOF){
nIndex=0;
for(int i=0; i<n; ++i){
scanf("%lf%lf",&p,&r);
if(w/2>=r)
continue; //直径小于宽度的不考虑
double t=sqrt(r*r-w*w/4.0);
arr[nIndex].left=p-t;
arr[nIndex].right=p+t;
++nIndex;
}

sort(arr,arr+nIndex);
int cnt=0;
double left=0, right=0;
bool flag=false;

if(arr[0].left <= 0 ){
int i=0;

while(i < nIndex){

int j=i;
while(j<nIndex && left>=arr[j].left){
if(arr[j].right > right)
right=arr[j].right;
++j;
}
if(j==i) break;  // 如果上面的循环体没有执行，说明之后都没有满足的了

++cnt;
left=right;
i=j;

if(left>=l){
flag=true;
break;
}
}
}
if(flag) printf("%d\n", cnt);
else printf("-1\n");
}
return 0;
}

UVa10905 孩子们的游戏

当作字符串从大到小排序 重点是cmp写法

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
#include<map>
#define LL long long
#define INF 1000000000
#define eps 1e-10
#define sqr(x) (x)*(x)
#define pa pair<int,int>
#define cyc(i,x,y) for(int i=(x);i<=(y);i++)
#define cy2(i,x,y) for(int i=(x);i>=(y);i--)
using namespace std;
inline int read()
{
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();}
return x*f;
}
string str[51];
int cmp(string a,string b)
{
return a+b>b+a;
}
int n;
int main()
{
//  freopen("input.in","r",stdin);
//  freopen("output.out","w",stdout);
n=read();
while(n)
{
cyc(i,1,n)cin>>str[i];
sort(str+1,str+n+1,cmp);
cyc(i,1,n)cout<<str[i];cout<<endl;
n=read();
}
return 0;
}

UVa10340 子序列

扫描就好了

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
#include<map>
#define LL long long
#define INF 1000000000
#define eps 1e-10
#define sqr(x) (x)*(x)
#define pa pair<int,int>
#define cyc(i,x,y) for(int i=(x);i<=(y);i++)
#define cy2(i,x,y) for(int i=(x);i>=(y);i--)
using namespace std;
inline int read()
{
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();}
return x*f;
}
char s1[101000],s2[101000];
int main()
{
//  freopen("input.in","r",stdin);
//  freopen("output.out","w",stdout);
while(~scanf("%s %s",s1,s2))
{
int i=0,len1=strlen(s1),len2=strlen(s2);
cyc(j,0,len2-1)
{
if(s1[i]==s2[j])i++;
}
if(i!=len1)printf("No\n");
else printf("Yes\n");
}
return 0;
}

LA3266 田忌赛马

贪心，细节

#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#include<vector>
#include<map>
#include<queue>
#include<stack>
#include<string>
#include<map>
using namespace std;
#define LL long long
const int maxn=1005;
int A[maxn],B[maxn];
int main(){
int n;
while(scanf("%d",&n)&&n){
for(int i=0;i<n;i++) scanf("%d",&A[i]);
for(int i=0;i<n;i++) scanf("%d",&B[i]);
sort(A,A+n);
sort(B,B+n);
int win=0,tag=0,i=0,j=n-1;
while(true){
int a1=A[i+tag],an=A[j],b1=B[i],bn=B[j-tag];
if(i+tag>j) break;
if(i+tag==j){
if(a1>b1) win++;
if(a1<b1) win--;
break;
}
if(a1>b1&&an>bn){
i++;j--;win+=2;
}
else if(a1>b1){i++;win++;}
else if(an>bn){j--;win++;}
else{
tag++;
if(a1<bn) win--;
}
}
printf("%d\n",win*200);
}
return 0;
}

UVa11134

贪心 两次区间选点

#include<set>
#include<stdio.h>
#include<algorithm>

#define N 5000 + 10

using namespace std;

typedef struct
{
int l ,r ,id;
}EDGE;

int AnsX
,AnsY
;
EDGE X
,Y
;
set<int>set1 ,set2;

bool camp(EDGE a ,EDGE b)
{
return a.r < b.r;
}

int main ()
{
int i ,n;
int x1 ,x2 ,y1 ,y2;
while(~scanf("%d" ,&n) && n)
{
set1.clear() ,set2.clear();
for(i = 1 ;i <= n ;i ++)
{
scanf("%d %d %d %d" ,&x1 ,&y1 ,&x2 ,&y2);
X[i].l = x1 ,X[i].r = x2;
Y[i].l = y1 ,Y[i].r = y2;
X[i].id = Y[i].id = i;
set1.insert(i);
set2.insert(i);
}
set1.insert(10000000);
set2.insert(10000000);
sort(X + 1 ,X + n + 1 ,camp);
sort(Y + 1 ,Y + n + 1 ,camp);
int mk = 0;
for(i = 1 ;i <= n && !mk ;i ++)
{
int tmpx = *set1.lower_bound(X[i].l);
if(tmpx > X[i].r) mk = 1;
AnsX[X[i].id] = tmpx;
set1.erase(tmpx);

int tmpy = *set2.lower_bound(Y[i].l);
if(tmpy > Y[i].r) mk = 1;
AnsY[Y[i].id] = tmpy;
set2.erase(tmpy);
}

if(mk)
{
puts("IMPOSSIBLE");
continue;
}
for(i = 1 ;i <= n ;i ++)
printf("%d %d\n" ,AnsX[i] ,AnsY[i]);
}
return 0;
}

UVa11389 巴士司机问题

容易想错

#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <cmath>

using namespace std;

int morni[101];
int after[101];

int cmp1(int a, int b){ return a < b; }
int cmp2(int a, int b){ return a > b; }

int main()
{
int n,d,r;
while (~scanf("%d%d%d",&n,&d,&r) && n) {
for (int i = 0 ; i < n ; ++ i)
scanf("%d",&morni[i]);
for (int i = 0 ; i < n ; ++ i)
scanf("%d",&after[i]);
sort(morni, morni+n, cmp1);
sort(after, after+n, cmp2);
int sum = 0;
for (int i = 0 ; i < n ; ++ i)
if (morni[i]+after[i] > d)
sum += r*(morni[i]+after[i]-d);

printf("%d\n",sum);
}
return 0;
}

UVa108 最大连续子序列和

算是dp吧 f[i]表示以i结尾（包含i）的最大连续序列和

f[i]=max(f[i-1],0)+a[i],ans=max(ans,f[i])

#include<cstdio>
#include<iostream>
#include<cmath>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<queue>
#include<vector>
#include<map>
#define LL long long
#define INF 1000000000
#define eps 1e-10
#define sqr(x) (x)*(x)
#define pa pair<int,int>
#define cyc(i,x,y) for(int i=(x);i<=(y);i++)
#define cy2(i,x,y) for(int i=(x);i>=(y);i--)
using namespace std;
inline int read()
{
int x=0,f=1;char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=10*x+ch-'0';ch=getchar();}
return x*f;
}
int a[101][101],f[101][101],an[101],n,T,tmp[101];
int main()
{
//  freopen("input.in","r",stdin);
//  freopen("output.out","w",stdout);
int ans=-INF;
n=read();
cyc(i,1,n)cyc(j,1,n)
a[i][j]=read();
cyc(i,1,n)cyc(j,1,n)
f[i][j]=f[i-1][j]+a[i][j];
cyc(i,1,n)cyc(j,i,n)
{
cyc(k,1,n)tmp[k]=f[j][k]-f[i-1][k];
an[1]=tmp[1];
cyc(k,2,n)
{
if(an[k-1]>0)an[k]=an[k-1]+tmp[k];
else an[k]=tmp[k];
ans=max(ans,an[k]);
}
}
printf("%d\n",ans);

return 0;
}

UVa10125 和集

a+b=d-c 枚举hash查找

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
using namespace std;

const int MAXN = 10000003;
const int MAXSIZE = 1030;

int n;
int rear;

struct node
{
int i, j;
}st[MAXSIZE*MAXSIZE];

int first[MAXN], next[MAXSIZE*MAXSIZE];
int A[MAXSIZE];
int sum[MAXSIZE*MAXSIZE];

void init()
{
rear = 0;
memset(first, -1, sizeof(first));
}

int hash(int s)
{
int h = s & 0x7fffffff;
return h % MAXN;
}

void insert(int s)
{
int h = hash(sum[s]);
next[s] = first[h];
first[h] = s;
}

int find(int i, int j, int s)
{
int h = hash(s);
for(int v = first[h]; v != -1; v = next[v])
{
if(s == sum[v] && st[v].i != i && st[v].i != j && st[v].j != i && st[v].j != j) return 1;
}
return 0;
}

void read_case()
{
init();
for(int i = 0; i < n; i++) scanf("%d", &A[i]);
sort(A, A+n);
for(int i = 0; i < n; i++)
{
for(int j = i+1; j < n; j++)
{
st[rear].i = i, st[rear].j = j;
sum[rear] = A[i]+A[j];
insert(rear);
rear++;
}
}
}

void solve()
{
read_case();
for(int i = n-1; i >= 0; i--)
{
for(int j = 0; j < n; j++) if(i != j)
{
if(find(i, j, A[i]-A[j]))
{
printf("%d\n", A[i]);
return ;
}
}
}
printf("no solution\n");
}

int main()
{
while(scanf("%d", &n) && n)
{
solve();
}
return 0;
}

UVa10763 交换学生

#include<stdio.h>
#include<string.h>
int G[1000][1000],n;
int check()
{
int i,j;
for(i=0;i<1000;i++)
for(j=0;j<1000;j++)
if(G[i][j]!=0)
return 0;
return 1;
}
int main()
{
int i,j,u,v;
while(1)
{
scanf("%d",&n);
if(n==0)
break;
memset(G,0,sizeof(G));
for(i=0;i<n;i++)
{
scanf("%d%d",&u,&v);
G[u][v]++;
G[v][u]--;
}
if(check())
printf("YES\n");
else
printf("NO\n");
}
return 0;
}