1513-Palindrome（LCS）

http://acm.hdu.edu.cn/showproblem.php?pid=1513

#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
using namespace std;

char s1[5005],s2[5005];
int dp[2][5005],n;

void LCS()
{
    int i,j;
    memset(dp,0,sizeof(dp));
    for(i = 1;i<=n;i++)
    {
        for(j = 1;j<=n;j++)
        {
            int x = i%2;
            int y = 1-x;
            if(s1[i-1]==s2[j-1])
            dp[x][j] = dp[y][j-1]+1;
            else
            dp[x][j] = max(dp[y][j],dp[x][j-1]);
        }
    }
}

int main()
{
    int i,j;
    while(~scanf("%d",&n))
    {
        scanf("%s",s1);
        for(i = 0;i<n;i++)
        s2[i] = s1[n-1-i];
        s2[i] = '';
        LCS();
        printf("%d
",n-dp[n%2][n]);
    }

    return 0;
}