题解 | 括号的匹配

#include <iostream>
#include <map>
#include <stack>
using namespace std;

int main() {
    int a;
    cin >> a;
    map<char, char> m = {{'{','}'}, {'[',']'}, {'(',')'}, {'<','>'}};
    map<char, int> level = {{'{',1}, {'[',2}, {'(',3}, {'<',4}};
    while (a--) {
        string r;
        cin >> r;
        stack<char> st;
        bool valid = true;
        
        for (char ch : r) {
            if (ch == '{' || ch == '[' || ch == '(' || ch == '<') {
                if (!st.empty() && level[ch] < level[st.top()]) {
                    valid = false;
                    break;
                }
                st.push(ch);
            } else {
                if (st.empty() || m[st.top()] != ch) {
                    valid = false;
                    break;
                }
                st.pop();
            }
        }
        
        cout << (valid && st.empty() ? "YES" : "NO") << "\n";
    }
    return 0;
}