Manacher算法（最长子回文串）

来源：互联网发布：三线开花及选股源码编辑：程序博客网时间：2024/04/29 14:26

HDU3068 POJ3974

#include <iostream>#include <cstdio>#include <algorithm>#include <map>#include <vector>#include <set>#include <string>#include <cstring>#define INT_MIN 0x80000000#define INT_MAX 0xffffffff#define N 1001000#define MAX(a,b) (a)>(b)?(a):(b)#define MIN(a,b) (a)<(b)?(a):(b)#define LL long long#define debug(x) cout<<#x<<":"<<(x)<<endl;using namespace std;char s[N<<1];int p[N<<1];int main(){    //freopen("1.txt", "r", stdin);    //freopen("11.txt", "w", stdout);    //ios::sync_with_stdio(false);    while( ~scanf("%s", s) )    {        int len = strlen(s);        int id = 0 , max_len = 0;        for(int i=len; i>=0; i--)        {            s[i+i+2] = s[i];            s[i+i+1] = '#';        }        s[0] = '*';        for(int i=2; i<2*len+1; i++)        {            if(p[id]+id>i) p[i] = min(p[id-(i-id)], p[id]-(i-id));            else p[i] = 1;            while( s[i-p[i]] == s[i+p[i]] ) ++p[i];            if( id+p[id] < i+p[i] ) id = i;            if( max_len < p[i] ) max_len = p[i];        }        printf("%d\n", max_len-1);    }    return 0;}

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