使用指针查找不平衡括号之间的字符位置

#include <iostream>
#include <stack>
#include <string>

int main() {
    std::string str = "((abc){def})ghi[jkl]";

    std::stack<int> st;
    for (int i = 0; i < str.length(); i++) {
        if (str[i] == '(' || str[i] == '[' || str[i] == '{') {
            st.push(i);
        } else if (str[i] == ')' || str[i] == ']' || str[i] == '}') {
            if (st.empty()) {
                std::cout << "Unbalanced bracket at position " << i << std::endl;
            } else {
                int leftPos = st.top();
                st.pop();
                if ((str[i] == ')' && str[leftPos] != '(') ||
                    (str[i] == ']' && str[leftPos] != '[') ||
                    (str[i] == '}' && str[leftPos] != '{')) {
                    std::cout << "Unbalanced bracket at position " << i << std::endl;
                }
            }
        }
    }

    while (!st.empty()) {
        int leftPos = st.top();
        st.pop();
        std::cout << "Unbalanced bracket at position " << leftPos << std::endl;
    }

    return 0;
}