#CODEFORCESP7369. Extra-terrestrial Intelligence
Extra-terrestrial Intelligence
Extra-terrestrial Intelligence
题目背景
注意这题要加上这个:
freopen("input.txt","r",stdin);
freopen("output.txt","w",stdout);
题面翻译
给定一 序列,试问其中的 是否等距.若等距则输出YES
,否则输出NO
。
Translated by @稀神探女
input: input.txt
output: output.txt
题目描述
Recently Vasya got interested in finding extra-terrestrial intelligence. He made a simple extra-terrestrial signals’ receiver and was keeping a record of the signals for days in a row. Each of those days Vasya wrote a 1 in his notebook if he had received a signal that day and a 0 if he hadn’t. Vasya thinks that he has found extra-terrestrial intelligence if there is a system in the way the signals has been received, i.e. if all the intervals between successive signals are equal. Otherwise, Vasya thinks that the signals were sent by some stupid aliens no one cares about. Help Vasya to deduce from the information given by the receiver if he has found extra-terrestrial intelligence or not.
输入格式
The first line contains integer ( ) — amount of days during which Vasya checked if there were any signals. The second line contains characters 1 or 0 — the record Vasya kept each of those days. It’s guaranteed that the given record sequence contains at least three 1s.
输出格式
If Vasya has found extra-terrestrial intelligence, output YES, otherwise output NO.
样例 #1
样例输入 #1
8
00111000
样例输出 #1
YES
样例 #2
样例输入 #2
7
1001011
样例输出 #2
NO
样例 #3
样例输入 #3
7
1010100
样例输出 #3
YES