#include<iostream> #include<stack> #include<string> using namespace std; stack<int>s1; stack<char>s2; int sum; int opera(int a,char b,int c) { if (b == 'x')return a * c; else if (b == '/')return a / c; else if (b == '+')return a + c; else if (b == '-')return a - c; } int calculate(string s) { sum = 0; for (int i = 0; i < 7; i++) { if (i == 1 || i == 3 || i == 5) { if (s[i] == '+' || s[i] == '-') { s2.push(s[i]); } else if (s[i] == 'x' || s[i] == '/') { int top = s1.top(); int temp = opera(top, s[i], s[i + 1]); s1.push(temp); i++; } } else s1.push(s[i] - '0'); } int tmp1[4], tmp2[3]; int index1 = 3; int index2 = 2; while (!s1.empty()) { tmp1[index1--] = s1.top(); s1.pop(); } while (!s2.empty()) { tmp2[index2--] = s2.top(); s2.pop(); } for (int i = 0; i < 4; i++) { sum += opera(tmp1[i], tmp2[i], tmp1[i + 1]); } return sum; } int main() { int n; cin >> n;//n行整数 string s ; for (int i = 0; i < n; i++) { cin >> s; calculate(s); if (sum == 24) { cout << "Yes" << endl; } else cout << "No" << endl; } system("pause"); }修改以上代码

以下是修改后的代码，主要修改了calculate函数中的逻辑：

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

stack<int> s1;
stack<char> s2;

int opera(int a, char b, int c) {
    if (b == 'x') return a * c;
    else if (b == '/') return a / c;
    else if (b == '+') return a + c;
    else if (b == '-') return a - c;
}

int calculate(string s) {
    // 清空栈
    while (!s1.empty()) s1.pop();
    while (!s2.empty()) s2.pop();

    int sum = 0;
    for (int i = 0; i < 7; i++) {
        if (i == 1 || i == 3 || i == 5) {
            if (s[i] == '+' || s[i] == '-') {
                s2.push(s[i]);
            } else if (s[i] == 'x' || s[i] == '/') {
                int top = s1.top();
                s1.pop(); // 弹出栈顶元素
                int temp = opera(top, s[i], s[i + 1]);
                s1.push(temp);
                i++;
            }
        } else {
            s1.push(s[i] - '0');
        }
    }

    // 计算栈中剩余的元素
    while (!s2.empty()) {
        int a = s1.top();
        s1.pop();
        int b = s1.top();
        s1.pop();
        char op = s2.top();
        s2.pop();
        s1.push(opera(b, op, a));
    }

    return s1.top(); // 返回栈中最后剩余的元素
}

int main() {
    int n;
    cin >> n;
    string s;
    for (int i = 0; i < n; i++) {
        cin >> s;
        if (calculate(s) == 24) {
            cout << "Yes" << endl;
        } else {
            cout << "No" << endl;
        }
    }
    return 0;
}

修改的主要内容如下：

1. 在calculate函数中加入了清空栈的操作，保证每次计算之前栈中没有残留元素。

2. 修改了计算逻辑，先将字符串中的元素依次入栈，然后按照运算符的优先级进行计算，最终返回栈中剩余的元素。

3. 在主函数中直接调用calculate函数，并根据返回值判断是否等于24输出结果。