HDU3068 manacher算法

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <iostream>

using namespace std;
const int maxn = 110000*2+100;
char input[maxn];
char a[maxn]; int p[maxn]; //manacher

void manacher(char *s){
    int len = strlen(s+1);
    int m = 2*len+1;
    for(int i=1; i<=len; i++){
        a[i<<1] = s[i];
        a[i<<1|1] = ‘#‘;
    }
    a[0] = ‘+‘; a[1] = ‘#‘; a[m+1] = ‘-‘;
   // cout<<a<<endl;
    int mx=0, idx;
    int res = 0;
    for(int i=1; i<=m; i++) {
        if(mx > i)
            p[i] = min(p[2*idx-i], mx-i);
        else
            p[i] = 1;
        for(; a[i-p[i]]==a[i+p[i]]; p[i]++);
        if(p[i]+i > mx) mx = p[i]+i, idx=i;
        res = max(res, p[i]);
    }
    cout<<res-1<<endl;
//    for(int i=1; i<=m; i++)
//        cout<<p[i]<<‘ ‘;
//    cout<<endl;
}

int main() {
    while(scanf("%s", input+1) != EOF){
        manacher(input);
    }
    return 0;
}