[백준 1935] 후위 표기식2 - 자료구조

Author: HiiWee

hoseok/week02/Boj1935.java

@@ -0,0 +1,47 @@
+/*
+    후위 표기식은 스택하나로 계산이 가능
+*/
+
+import java.io.*;
+import java.util.*;
+
+class Main {
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+        int n = Integer.parseInt(br.readLine());
+        String line = br.readLine();
+        Stack<Double> stack = new Stack<>();
+
+        int[] numbers = new int[n];
+
+        for (int i = 0; i < n; i++) {
+            numbers[i] = Integer.parseInt(br.readLine());
+        }
+
+        for (char input : line.toCharArray()) {
+            if (input >= 65 && input <= 90) {
+                stack.push((double) numbers[input - 'A']);
+            } else {
+                stack.push(calculate(stack.pop(), stack.pop(), input));
+            }
+        }
+
+        bw.write(String.format("%.2f", stack.pop()));
+        bw.flush();
+        bw.close();
+    }
+
+    public static double calculate(double op2, double op1, char operator) {
+        if (operator == '+') {
+            return op1 + op2;
+        }
+        if (operator == '-') {
+            return op1 - op2;
+        }
+        if (operator == '/') {
+            return op1 / op2;
+        }
+        return op1 * op2;
+    }
+}