POJ 2955 —— Brackets

#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>
using namespace std;

char s[105];
int dp[105][105];
const char end[4] = "end";

int main ()
{
    while(scanf("%s", s) != EOF && strcmp(s, end)) {
        int len = strlen(s);
        for(int i=0; i<len-1; i++) {
            dp[i][i+1] = 2*(s[i]==‘(‘ && s[i+1]==‘)‘ || s[i]==‘[‘ && s[i+1]==‘]‘);
        }
        
        for(int step=2; step<len; step++) {
            for(int i=0; i+step<len; i++) {
                int j = i+step;
                
                //删去不必要的字符 
                if(s[i]!=‘(‘ && s[i]!=‘[‘) {
                    dp[i][j] = dp[i+1][j];
                } else if(s[j]!=‘)‘ && s[j]!=‘]‘) {
                    dp[i][j] = dp[i][j-1];
                }
                else {
                    dp[i][j]=0;
                    if(s[i]==‘(‘ && s[j]==‘)‘ || s[i]==‘[‘ && s[j]==‘]‘) {
                        dp[i][j] = dp[i+1][j-1]+2;
                    }
                    for(int k=i; k<j; k++) {
                        dp[i][j] = max(dp[i][j], dp[i][k] + dp[k+1][j]);
                    }
                }
            }
        }
        printf("%d\n", dp[0][len-1]);
    }
    
    return 0;
}