视频讲解：https://www.bilibili.com/video/BV1E44y1E7Jc?p=2&share_source=copy_web

#include<iostream>
#include<string.h>
#include<algorithm>
#include<math.h>
#include<vector>
#include<map>
#include<stack>
using namespace std;
typedef long long ll;
const ll md=1e5;
stack<ll> num;
stack<char> op;
map <char,ll> ma;
ll a,b;
int main(){
    ma['+']=1;
    ma['*']=2;
    string s;
    cin>>s;
    for(int i=0;i<s.size();i++){
        if(s[i]>='0'&&s[i]<='9'){
        	int x=0;
        	while(s[i]>='0'&&s[i]<='9'){
        		x=x*10+s[i]-'0';
        		i++;
			}
			i--;
			num.push(x);
		}


        else{
            if(op.empty())op.push(s[i]);
            else{
                while(!op.empty()&&ma[op.top()]>=ma[s[i]]){
                    if(op.top()=='+'){
                        a=num.top();
                        num.pop();
                        b=num.top();
                        num.pop();
                        num.push((a+b)%md);
                    }
                    else{
                        a=num.top();
                        num.pop();
                        b=num.top();
                        num.pop();
                        num.push((a%md*b%md)%md);
                    }
                    op.pop();
                }
                op.push(s[i]);
            }
        }
    }
    ll ans=0;
    while(num.size()>=2){
    	a=num.top();
    	num.pop();
		b=num.top();
		num.pop();
		if(op.top()=='+'){
			num.push((a+b)%md);
			op.pop();
		}
		else{
			num.push((a%md*b%md)%md);
			op.pop();
		}
	}
	ans=num.top();
    if(ans>=10000)cout<<ans%10000;
    else cout<<ans;

    return 0;
}

浅写一个java的

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Stack;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String expression = in.nextLine();//注意表达式
        List<String> infixExpressionList = toInfixExpressionList(expression);
//       System.out.println("中缀表达式对应的List=" + infixExpressionList);
        List<String> suffixExpreesionList = parseSuffExpressionList(infixExpressionList);
//        System.out.println("后缀表达式对应的List" + suffixExpreesionList); //ArrayList [1,2,3,+,4,*,+,5,–]
        //        String suffixExpression = "4 5 * 8 - 60 + 8 2 / +"; // 76
//        List<String> list = getListString(suffixExpression);
        int  res = calculate(suffixExpreesionList);
        System.out.println(res % 10000);
    }
    public static List<String> parseSuffExpressionList(List<String> ls){
        Stack<String> s1 = new Stack<>();
//        Stack<String> s2 = new Stack<>();
        List<String> s2 = new ArrayList<>();

        for(String item : ls){
            if(item.matches("\\d+")){
                s2.add(item);
            }else if(item.equals("(")){
                s1.push(item);
            }else if(item.equals(")")){
                while(!s1.peek().equals("(")){
                    s2.add(s1.pop());
                }
                s1.pop();
            }else {
                while(s1.size() != 0 && Operation.getValue(s1.peek())>=Operation.getValue(item)){
                    s2.add(s1.pop());
                }
                s1.push(item);
            }
        }
        while(s1.size() != 0){
            s2.add(s1.pop());
        }
        return s2;
    }

    public static List<String> toInfixExpressionList(String s){
        List<String> list = new ArrayList<String>();
        int i = 0;
        String str;
        char c;
        do{
            if((c = s.charAt(i)) <48 || (c = s.charAt(i)) > 57){
                list.add("" + c);//转换成字符串
                i++;
            }else {
                str = "";
                while( i < s.length() && (c = s.charAt(i)) >= 48 && (c = s.charAt(i)) <= 57){
                    str += c;
                    i++;
                }
                list.add(str);
            }
        }while(i < s.length());
        return list;
    }
    public static List<String> getListString(String suffixExpression) {
        String split[] = suffixExpression.split(" ");
        List<String> list = new ArrayList<>();
        for (String element : split) {
            list.add(element);
        }
        return (list);
    }

    public static int calculate(List<String> ls) {
        Stack<String> stack = new Stack<String>();
        for (String element : ls) {
            if (element.matches("\\d+")) {
                stack.push(element);
            } else {
                int num2 = Integer.parseInt(stack.pop());
                int num1 = Integer.parseInt(stack.pop());
                int res = 0;
                if (element.equals("+")) {
                    res = (num1 + num2) % 10000;
                } else if (element.equals("-")) {
                    res = (num1 - num2) % 10000;
                } else if (element.equals("*")) {
                    res = (num1 * num2) % 10000;
                } else if (element.equals("/")) {
                    res = (num1 / num2) % 10000;
                } else {
                    throw new RuntimeException("运算符有误");
                }
                stack.push("" + res);
            }
        }
        return Integer.parseInt(stack.pop());
    }
}
class Operation{
    private static int ADD = 1;
    private static int SUB = 1;
    private static int MUL = 2;
    private static int DIV = 2;

    public static int getValue(String operation){
        int result = 0;
        switch(operation){
            case "+":
                result = ADD;
                break;
            case "-":
                result = SUB;
                break;
            case "*":
                result = MUL;
                break;
            case "/":
                result = DIV;
                break;
            default:
                break;
        }
        return result;
    }
}