Update Basic Calculator.java

varunu28 · web-flow · commit 6c7a794d1082 · 2021-09-11T09:11:49.000-07:00
diff --git a/Hard/Basic Calculator.java b/Hard/Basic Calculator.java
@@ -1,55 +1,41 @@
 class Solution {
-    public static  int calculate(String s) {
-        Stack<Integer> stack = new Stack<>();
-        int res = 0;
-        int num = 0;
-        int sign = 1;
-        boolean hasNumberStarted = false;
-
-        for (int i=0; i<s.length(); i++) {
-            char c = s.charAt(i);
-
-            if (Character.isDigit(c)) {
-                hasNumberStarted = true;
-                num = num * 10 + (int) (c - '0');
-            }
-            else if (c == '+') {
-                if(!hasNumberStarted) {
-                    continue;
-                }
-                hasNumberStarted = false;
-                res += sign * num;
-                num = 0;
-                sign = 1;
-            }
-            else if (c == '-') {
-                if(!hasNumberStarted) {
-                    sign *= -1;
-                    continue;
-                }
-                hasNumberStarted = false;
-                res += sign * num;
-                num = 0;
-                sign = -1;
-            }
-            else if (c == '(') {
-                stack.push(res);
-                stack.push(sign);
-                sign = 1;
-                res = 0;
-            }
-            else if (c == ')') {
-                res += sign * num;
-                num = 0;
-                res *= stack.pop();
-                res += stack.pop();
-            }
+  public static  int calculate(String s) {
+    Stack<Integer> stack = new Stack<>();
+    int res = 0;
+    int num = 0;
+    int sign = 1;
+    boolean hasNumberStarted = false;
+    for (int i = 0; i < s.length(); i++) {
+      char c = s.charAt(i);
+      if (Character.isDigit(c)) {
+        hasNumberStarted = true;
+        num = num * 10 + (int) (c - '0');
+      } else if (c == '+' && hasNumberStarted) {
+        hasNumberStarted = false;
+        res += sign * num;
+        num = 0;
+        sign = 1;
+      } else if (c == '-') {
+        if(!hasNumberStarted) {
+          sign *= -1;
+          continue;
         }
-
-        if (num != 0) {
-            res += sign * num;
-        }
-
-        return res;
+        hasNumberStarted = false;
+        res += sign * num;
+        num = 0;
+        sign = -1;
+      } else if (c == '(') {
+        stack.push(res);
+        stack.push(sign);
+        sign = 1;
+        res = 0;
+      } else if (c == ')') {
+        res += sign * num;
+        num = 0;
+        res *= stack.pop(); // For sign
+        res += stack.pop(); // Adding the num in stack
+      }
     }
+    return res + (num != 0 ? sign * num : 0);
+  }
 }
