[leet] basic calculator

Author: hyeonbinHur

허현빈/9주차/Basic Calculator.js

@@ -0,0 +1,41 @@
+/**
+ * @param {string} s
+ * @return {number}
+ */
+var calculate = function (s) {
+  let res = 0;
+  let num = 0;
+  let sign = 1;
+  const stack = [];
+
+  for (let i = 0; i < s.length; i++) {
+    const ch = s[i];
+
+    if (ch >= "0" && ch <= "9") {
+      num = num * 10 + (ch.charCodeAt(0) - 48);
+    } else if (ch === "+") {
+      res += sign * num;
+      num = 0;
+      sign = 1;
+    } else if (ch === "-") {
+      res += sign * num;
+      num = 0;
+      sign = -1;
+    } else if (ch === "(") {
+      stack.push(res);
+      stack.push(sign);
+      res = 0;
+      num = 0;
+      sign = 1;
+    } else if (ch === ")") {
+      res += sign * num;
+      num = 0;
+
+      const prevSign = stack.pop();
+      const prevRes = stack.pop();
+
+      res = prevRes + prevSign * res;
+    }
+  }
+  return res + sign * num;
+};