经典的括号匹配问题

题目：括号配对问题

#include <iostream>
#include <string>

using namespace std;

int main()
{
     int t;
     cin >> t;
     while(t--)
     {
          string s;
          cin >> s;
          int num = 0;
          while(s.length() >= 2 && num != s.length())
          {
               num = s.length();
               for(int i = 0;i < s.length(); ++i)
                    if((s[i] == '(' && s[i + 1] == ')') || (s[i] == '[' && s[i + 1] == ']'))
                          s.erase(s.begin() + i, s.begin() + i + 2);
          }
          if(s.length() == 0)
                cout << "Yes" << endl;
          else
                cout << "No" << endl;
    }
    return 0;
}

 题目：Longest Regular Bracket Sequence

#include <cstdio>
#include <vector>
#include <cstring>

using namespace std;

int dp[1234567];
char s[1234567];

int main() 
{
    gets(s);
    int n = strlen(s);
    vector<int> st;
    memset(dp, 0, sizeof(dp));
    for (int i = 0; i < n; i++) 
    {
        if (s[i] == '(') 
            st.push_back(i);
        else 
        {
            if (!st.empty()) 
            {
                int he = st[st.size() - 1];
                st.pop_back();
                if (!he) dp[i] = i + 1;
                else dp[i] = dp[he - 1] + i - he + 1;
            }
        }       
    }   
    int ans = 0, cnt = 1;
    for (int i = 0; i < n; i++) 
    {
        if (dp[i] == ans) 
            cnt++;
        else if (dp[i] > ans) 
        {
            ans = dp[i];
            cnt = 1;
        }
    }
    if (!ans) cnt = 1;
    printf("%d %d\n", ans, cnt);
    return 0;
} 

 题目：Regular Bracket Sequence

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

int main()
{
    string s;
    int cur = 0 , ans = 0;
    cin>>s;
    for(int i = 0 ; i < s.length() ; i++)
    {
        if(s[i] == '(')
            cur ++ , ans ++;
        if(s[i] == ')' && cur > 0)
            cur -- , ans ++;
    }
    cout<<ans - cur<<endl;
    return 0;
}

 

题目：括号匹配（二）

#include <iostream>
#include <string.h>
#include <string>

const int N = 105;

bool is(char a,char b)
{
    if(a=='(' && b==')') return true;
    if(a=='[' && b==']') return true;
    return false;
}

int main()
{
    int t,i,j,k;
    int dp[N][N];
    std::string s;
    std::cin>>t;
    while(t--)
    {
        std::cin>>s;
        memset(dp,0,sizeof(dp));
        for(i=0;i<=s.length();i++)
           dp[i][i]=1;
        for(i=2;i<=s.length();i++)
        {
            for(j=i-1;j>=1;j--)
            {
                dp[j][i]=dp[j][i-1]+1;
                for(k=j;k<i;k++)
                {
                    if(is(s[k-1],s[i-1]))
                       dp[j][i]=std::min(dp[j][i],dp[j][k-1]+dp[k+1][i-1]);
                }
            }
        }
        std::cout<<dp[1][s.length()]<<std::endl;
    }
    return 0;
}