Brackets POJ 2955 区间dp

题意：给出一个的只有'(',')','[',']'四种括号组成的字符串，求最长长度多少，end结束

思路：区间dp，dp[i][j]表示区间[i,j]符合要求的长度

#include<iostream>
#include<algorithm>
#include<cstring>
#include<stack>
#include<cmath>
#include<queue>
using namespace std;
#define ll long long
#define N 205
#define rep(i,l,r) for(i=l;i<=r;i++)
const int mod = 1e9 + 7;
const int INF = 0x3f3f3f3f;
#define eps 0.00000001//偏差值1e8
#define pi acos(-1.0)//高精度圆周率
const int maxp = 1010;                    //点的数量
int a[N];
int dp[N][N];
int sum[N];
int main()
{
    int i, j, k;
    int n, ret = 0, m, maxn = 0, count = 0;
    int t, x, len;
    char s[N];
    while (cin >> s+1)
    {
        if (strcmp(s+1,"end")==0)
            break;
        n = strlen(s+1);
        memset(dp, 0, sizeof(dp));
        rep(len,2,n)
        {
            rep(i, 1, n)
            {
                j = i + len - 1;
                if (j > n)break;
                if (s[i] == '(' && s[j] == ')' || s[i] == '[' && s[j] == ']')
                    dp[i][j] = dp[i + 1][j - 1] + 2;
                rep(k, i, j - 1)
                {
                        dp[i][j] = max(dp[i][j], dp[i][k] + dp[k + 1][j]);
                }
            }
        }
        cout << dp[1][n] << endl;
    }
}