13周练 F - Infinite Sequence 【数列性质】

F - Infinite SequenceTime Limit:1000MS     Memory Limit:262144KB     64bit IO Format:%I64d& %I64uSubmit StatusDescriptionVasya likes everything infinite. Now he is studying the properties of a sequence s, such that its first element is equal to a (s1 = a),and the difference between any two neighbouring elements is equal to c (si - si - 1 = c).In particular, Vasya wonders if his favourite integer bappears in this sequence, that is, there exists a positive integer i, suchthat si = b. Of course, you are the person he asks for a help.InputThe first line of the input contain three integers a, b and c ( - 109 ≤ a, b, c ≤ 109) —the first element of the sequence, Vasya's favorite number and the difference between any two neighbouring elements of the sequence, respectively.OutputIf b appears in the sequence s print "YES" (without quotes), otherwise print "NO"(without quotes).Sample InputInput

1 7 3

Output

YES

Input

10 10 0

Output

YES

Input

1 -4 5

Output

NO

Input

0 60 50

Output

NO

记住，一道数学数列性质题，按公差分三中情况：

（1）c==0;

（2）c>0,b-a>0;

（3）c<0,b-a<0

判断，b是否在数列中。

#include <cstdio>int main(){long long a,b,c;while(~scanf("%lld%lld%lld",&a,&b,&c)){if(c==0){if(a==b)printf("YES\n");elseprintf("NO\n");}else if(c>0){if((b-a)%c==0&&b-a>=0)printf("YES\n");elseprintf("NO\n");}else{if((b-a)%c==0&&b-a<=0)printf("YES\n");elseprintf("NO\n");}}return 0;}