大佬们帮忙看看，为什么只得到34分

P1449 后缀表达式

awawlove @ 2024-04-18 21:27:06

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
struct stack
{
    int data;
    struct stack* next;
};
void initstack(struct stack** L)
{
    *L = (struct stack*)malloc(sizeof(struct stack));
    (*L)->next = NULL;
}
void push(struct stack** L, int e)
{
    struct stack* s = (struct stack*)malloc(sizeof(struct stack));
    s->data = e;
    s->next = *L;
    *L = s;
}
int top(struct stack** L)
{
    struct stack* p, * s;
    s = *L;
    p = *L;
    int e;
    e = (*L)->data;
    p = (*L)->next;
    *L = p;
    s->next = NULL;
    free(s);

    return e;
}
int main()
{
    char *a;
    a = (char*)malloc(50*sizeof(char));
    struct stack* L;
    initstack(&L);
    int num = 0, count = 0;
    scanf("%s", a);
    int len_a, n, m;
    n = 0;
    m = 0;
    len_a = strlen(a);
    for (int i = 0; i < len_a; i++)
    {
        switch (a[i])
        {
        case '.':
            push(&L, num);
            num = 0;
            break;
        case '+':
            count = top(&L) + top(&L);
            push(&L, count);
            break;
        case '-':
            count = (-1) * (top(&L) - top(&L));
            push(&L, count);
            break;
        case '*':
            count = top(&L) * top(&L);
            push(&L, count);
            break;
        case '/':
            n = top(&L);
            m = top(&L);
            count = m / n;
            push(&L, count);
            break;
        case '@':
            break;
        default:
            num = num * 10 + (a[i] - '0');
        }
        n = 0;
        m = 0;
        count = 0;
    }
    free(a);
    printf("%d", top(&L));
}

by luogu_tanbozhi @ 2024-06-08 12:55:06

here

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

using namespace std;

bool isOperator(char c) {
    return c == '+' || c == '-' || c == '*' || c == '/';
}

int performOperation(char operation, int operand1, int operand2) {
    switch(operation) {
        case '+': return operand1 + operand2;
        case '-': return operand1 - operand2;
        case '*': return operand1 * operand2;
        case '/': return operand1 / operand2;
        default: return 0;
    }
}

int evaluatePostfix(const string& expression) {
    stack<int> operandStack;
    string operandStr;

    for (char c : expression) {
        if (c == '@') {
            break;
        } else if (c == '.') {
            int operand = stoi(operandStr);
            operandStack.push(operand);
            operandStr = "";
        } else if (isdigit(c) || c == '.') {
            operandStr += c;
        } else if (isOperator(c)) {
            int operand2 = operandStack.top();
            operandStack.pop();
            int operand1 = operandStack.top();
            operandStack.pop();
            int result = performOperation(c, operand1, operand2);
            operandStack.push(result);
        }
    }

    return operandStack.top();
}

int main() {
    string postfixExpression;
    getline(cin, postfixExpression);

    int result = evaluatePostfix(postfixExpression);

    cout << result << endl;

    return 0;
}

@awawlove

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