【HDOJ】1237 简单计算器

数据结构经典习题了，可以仅用一个栈，因为符号优先级很明显。

#include <stdio.h>

#define MAXNUM 205

double stack[MAXNUM];

int main() {
    int top;
    double m, n;
    char ch;

    while (scanf("%lf", &m) != EOF) {
        ch = getchar();
        if (ch=='\n') {
            if (m) {
                printf("%.2lf\n", m);   // input just one num.
                continue;
            }
            else
                break;
        }
        top = 0;
        stack[top++] = m;
        ch = getchar();
        while (scanf("%lf", &n) != EOF) {
            if (ch=='+') {
                stack[top++] = n;
            } else if (ch=='*') {
                m = stack[--top];
                stack[top++] = m*n;
            } else if (ch=='/') {
                m = stack[--top];
                stack[top++] = m/n;
            } else if (ch=='-') {
                stack[top++] = (0-n);
            }

            ch = getchar(); // get space nexto num
            if (ch=='\n')
                break;

            ch = getchar(); // get op
        }
        m = 0;
        while (top)
            m += stack[--top];
        printf("%.2lf\n", m);
    }

    return 0;
}