백준 알고리즘 문제 풀이 c/c++ -1935-

https://www.acmicpc.net/problem/1935

• 후위표기식이란?

• 참고링크 https://siyoon210.tistory.com/2

• 스택 활용

• 출력 형식 보기

#include <stdio.h>
#include <stack>
#include <string.h>
#include <cmath>

using namespace std;

int main(){
	
	int n; 
	scanf("%d", &n);

	char expression[110];
	scanf("%s", expression);

	int len = strlen(expression);

	double num[30];
	for (int i = 0; i < n; i++)
		scanf("%lf", &num[i]);


	stack <double> s;

	for (int i = 0; i < len; i++) {

		if (expression[i] == '+') {
			double n1 = s.top();
			s.pop();
			double n2 = s.top();
			s.pop();
			s.push(n2 + n1);
		}
		else if (expression[i] == '-') {
			double n1 = s.top();
			s.pop();
			double n2 = s.top();
			s.pop();
			s.push(n2 - n1);
		}
		else if (expression[i] == '*') {
			double n1 = s.top();
			s.pop();
			double n2 = s.top();
			s.pop();
			s.push(n2 * n1);
		}
		else if (expression[i] == '/') {
			double n1 = s.top();
			s.pop();
			double n2 = s.top();
			s.pop();
			s.push(n2 / n1);
		}
		else {
			int index = expression[i] - 65;
			s.push(num[index]);
		}

	}


	printf("%0.2lf", round(s.top() * 100) / 100);



	return 0;
}