hihocoder1032(最长回文子串manacher算法)

来源：互联网发布：数组的push和pop 编辑：程序博客网时间：2024/04/29 03:43

题目连接：点击打开链接

解题思路：

manacher算法的模板题。

完整代码：

#include <algorithm>#include <iostream>#include <cstring>#include <complex>#include <cstdio>#include <string>#include <cmath>#include <queue>using namespace std;typedef unsigned long long LL;const int MOD = int(1e9)+7;const int INF = 0x3f3f3f3f;const double EPS = 1e-9;const double PI = acos(-1.0); //M_PI;const int maxn = 2000001;int n;char s[maxn] , t[maxn];int len[maxn];void manacher(char t[]){    int t_len = strlen(t);    int mx = 0 , id;    for(int i = 1 ; i < t_len ; i ++)    {        if(mx > i)  len[i] = min(len[id * 2 - i] , mx - i);        else    len[i] = 1;        while(t[i + len[i]] == t[i - len[i]])     len[i] ++;        if(len[i] + i > mx)        {            mx = len[i] + i;            id = i;        }    }}void solve(char s[]){    int s_len = strlen(s);    int t_len = s_len * 2 + 2;    t[0] = '+';    for(int i = 0 ; i < t_len ; i ++)    {        t[i * 2 + 1] = '#';        t[i * 2 + 2] = s[i];    }    manacher(t);    int ans = -INF;    for(int i = 1 ; i < t_len ; i ++)        ans = max(ans , len[i]);    printf("%d\n" , ans - 1);}int main(){    #ifdef DoubleQ    freopen("in.txt","r",stdin);    #endif    while(~scanf("%d",&n))    {        for(int i = 0 ; i < n ; i ++)        {            scanf("%s" , s);            solve(s);        }    }    return 0;}

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