time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
Mike has a string s consisting of only lowercase English letters. He wants to change exactly one character from the string so that the resulting one is a palindrome.
A palindrome is a string that reads the same backward as forward, for example strings "z", "aaa", "aba", "abccba" are palindromes, but strings "codeforces", "reality", "ab" are not.
Input
The first and single line contains string s (1 ≤ |s| ≤ 15).
Output
Print "YES" (without quotes) if Mike can change exactly one character so that the resulting string is palindrome or "NO" (without quotes) otherwise.
Examples
input
abccaa
output
YES
input
abbcca
output
NO
input
abcda
output
YES
题目大意：是否可以改变一个字符，使得字符串恰好为回文串。
方法：检查字符串是否为回文，记录不同记录不同位点个数。如果字符串不是回文，且不同位点为一个，输出YES;如果位点为0（也就是回文串）且串长度为奇数（可以改变最中间的那个），则输出YES;如果前两条都不满足，输出NO。
代码：
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
using namespace std;
const int N=;
int main()
{
ios::sync_with_stdio(false);
cin.tie();
char s[N];
gets(s);
int cnt=;
for(int i=;i<strlen(s);i++)
{
if(s[i]!=s[strlen(s)-i-])cnt++;
}
if(cnt==)cout<<"YES"<<endl;
else
{
if(cnt==&&strlen(s)%)cout<<"YES"<<endl;
else cout<<"NO"<<endl;
}
return ;
}