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Mihahim has a string s. He wants to delete exactly one character from it so that the resulting string would be a palindrome. Determine if he can do it, and if he can, what character should be deleted.
The input contains a string s of length (2 ≤ |s| ≤ 200000), consisting of lowercase Latin letters.
If the solution exists, output «YES» (without quotes) in the first line. Then in the second line output a single integer x — the number of the character that should be removed from s so that the resulting string would be a palindrome. The characters in the string are numbered from 1. If there are several possible solutions, output any of them.
If the solution doesn‘t exist, output «NO» (without quotes).
evertree
YES
2
emerald
NO
aa
YES
2
从左右两边往中间移动，如果相同，l++，r--，如果不同，第一次循环i==0时，则让l++，第二次循环则让r--，最后判断不同的出现了几次。如果dif是0，l>=r代表本身就是回文，则去掉l位置的字符。
#include <cstring>
#include <cstdio>
#define N 100005
char s[N<<1];
int len,l,r,dif,at;
int main() {
scanf("%s",s);
len=strlen(s);
for(int i=0;i<2;i++){
dif=0;
l=0,r=len-1;
while(l<r){
if(s[l]!=s[r]){
dif++;
if(i){
at=r;
r--;
}else {
at=l;
l++;
}
}
if(s[l]==s[r]){
l++;
r--;
}
}
if(l>=r&&dif==0)at=l;
if(dif<2){
printf("YES\n%d\n",at+1);
break;
}
}
if(dif>1)puts("NO");
}
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原文地址：http://www.cnblogs.com/flipped/p/5749040.html
