求一个字符串的最长连续回文串（模板）

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Manacher算法

#include<vector>#include<iostream>using namespace std;const int N=300010;int n, p[N];char s[N], str[N];#define _min(x, y) ((x)<(y)?(x):(y))void kp(){    int i;    int mx = 0;    int id;for(i=n; str[i]!=0; i++)str[i] = 0; //没有这一句有问题。。就过不了ural1297，比如数据：ababa aba    for(i=1; i<n; i++)    {        if( mx > i )            p[i] = _min( p[2*id-i], p[id]+id-i );        else            p[i] = 1;        for(; str[i+p[i]] == str[i-p[i]]; p[i]++)            ;        if( p[i] + i > mx )        {            mx = p[i] + i;            id = i;        }    }}void init(){int i, j, k;str[0] = '$';str[1] = '#';for(i=0; i<n; i++){str[i*2+2] = s[i];str[i*2+3] = '#';}n = n*2+2;s[n] = 0;}int main(){int i, ans;while(scanf("%s", s)!=EOF){n = strlen(s);init();kp();ans = 0;for(i=0; i<n; i++)if(p[i]>ans)ans = p[i];printf("%d\n", ans-1);}return 0;}

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