update 007 solution

Author: Neil94n

solution/0007.Reverse Integer/Solution2.js

@@ -0,0 +1,31 @@
+/**
+ * @param {number} x
+ * @return {number}
+ */
+var reverse = function (x) {
+    const s = x + ""
+    let i = 0
+    let sign = 1
+    if (s[i] == "-") {
+        i++
+        sign = -1
+    }
+    if (s[i] == "+") {
+        i++
+    }
+    let num = 0
+    for (let j = s.length - 1; j >= i; j--) {
+        num = num * 10 + parseInt(s[j])
+    }
+    num *= sign
+    let max = 2
+    for (let n = 0; n < 30; n++){
+        max *= 2
+    }
+    if (num > max || num < -max){
+        return 0
+    }
+    return num
+};
+
+console.log(reverse(1563847412))