四则运算描述: 请实现如下接口 /* 功能：四则运算 * 输入：strExpression：字符串格式的算术表达式，如: "3+2*{1+2*[-4/(8-6)+7]}" * 返回：算术表达式的计算结果 */ public static int calculate(String strExpression) { /* 请实现*/ return 0; } 约束：pucExpression字符串中的有效字符包括[‘0’-‘9’],‘+’,‘-’, ‘*’,‘/’ ,‘(’， ‘)’,‘[’, ‘]’,‘{’ ,‘}’。pucExpression算术表达式的有效性由调用者保证;
知识点: 栈 题目来源: 内部整理 练习阶段: 中级 运行时间限制:10Sec内存限制:128MByte输入: 输入一个算术表达式输出: 得到计算结果样例输入:3+2*{1+2*[-4/(8-6)+7]}
样例输出:25
#include "stdio.h"#include "stdlib.h"#include "string.h"#define MAX_PATH 256char stack_all[MAX_PATH] = {0};char stack_symbol[MAX_PATH] = {0};char stack_num[MAX_PATH] = {0};int num_all=0;int num_symbol =0;int num_num = 0;int cal(int a,int b,char op){switch(op){case '+':return a+b;case '-':return a-b;case '*':return a*b;case '/':if (b==0){return 0;}return a/b;default:return 0;}}//有效字符是0-9int calculate(char *strExpression){int length = strlen(strExpression);for (int i=length-1;i>=0;i–){char t = strExpression[i];if(t=='*' || t=='/' || t==')' || t==']' || t=='}'){stack_symbol[num_symbol] = t;num_symbol++;}else if (t=='('){while(true){if (stack_symbol[num_symbol-1]==')'){num_symbol–;break;}stack_all[num_all]=stack_symbol[num_symbol-1];num_all++;num_symbol–;}}else if (t=='['){while(true){if (stack_symbol[num_symbol-1]==']'){num_symbol–;break;}stack_all[num_all]=stack_symbol[num_symbol-1];num_all++;num_symbol–;}}else if (t=='{'){while(true){if (stack_symbol[num_symbol-1]=='}'){num_symbol–;break;}stack_all[num_all]=stack_symbol[num_symbol-1];num_all++;num_symbol–;}}else if(t=='+' || t=='-'){while((stack_symbol[num_symbol-1]=='*' || stack_symbol[num_symbol-1]=='/') && num_symbol!=0 ){stack_all[num_all]=stack_symbol[num_symbol-1];num_all++;num_symbol–;}stack_symbol[num_symbol] = t;num_symbol++;}else{stack_all[num_all] = t;num_all++;}}for (int i=num_symbol-1;i>=0;i–){stack_all[num_all]=stack_symbol[i];num_all++;}for (int i=0;i<num_all;i++){char t = stack_all[i];if (t>='0'&&t<='9'){stack_num[num_num]=t-'0';num_num++;}else{stack_num[num_num-2] = cal(stack_num[num_num-1],stack_num[num_num-2],t);num_num–;}}return (int)stack_num[0];} void init(char *buffer,char *buffer2){int length = strlen(buffer);int k = 0;for (int i=0;i<length;i++){char t = buffer[i];if (t=='+'||t=='-'){if(i>=1 && (buffer[i-1]=='(' || buffer[i-1]=='[' || buffer[i-1]=='{')){//可以不使用括号//buffer2[k]='0';//k++;//buffer2[k]=buffer[i];//k++;buffer2[k]='(';k++;buffer2[k]='0';k++;buffer2[k]=buffer[i];k++;buffer2[k]=buffer[i+1];i++;k++;buffer2[k]=')';k++;}else{buffer2[k]=buffer[i];k++;}}else{buffer2[k]=buffer[i];k++;}}}/*2 34 68 10特比注意：负数需要补0为0-正数。*/int main(){int m=0,n=0;char buffer[MAX_PATH] = {0};gets(buffer);//char buffer[MAX_PATH] = "3+2*{1+2*[-4/(8-6)+7]}";char buffer2[MAX_PATH] = {0};init(buffer,buffer2);// printf(buffer2);// printf("\n");int ret = calculate(buffer2);//printf(stack_all);//printf("\n");printf("%d",ret);return 0;}
，你写PPT时，阿拉斯加的鳕鱼正跃出水面，
