表达式直接求值——分治做法

来源：互联网发布：c语言简单的图形编程编辑：程序博客网时间：2024/05/23 20:14

#include<stdio.h>#include<stdlib.h>#include<string.h>#include<math.h>#define MAXN 101char s[MAXN];int calac(int L, int R){    int i, p = -1, lv = 0;    int m = 0;        for (i = L; i <= R; i++){        switch (s[i]){            case '(': lv++; break;            case ')': lv--; break;            case '+':            case '-':                if(!lv) p = i; break;            case '*':            case '/':                if(!lv && p == -1) p = i;                break;            default:                m = m * 10 + s[i] - '0';        }    }        if (p == -1)       return s[L] == '(' ? calac(L + 1, R - 1) : m;        int a1 = calac(L, p - 1), a2 = calac(p + 1, R);       switch (s[p]){        case '+': return a1 + a2;        case '-': return a1 - a2;        case '*': return a1 * a2;        case '/': return a1 / a2;    }}int main(){    gets(s);        printf("%d\n", calac(0, strlen(s) - 1));        system("pause");        return 0;}

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