Create 7_reverse.ts

Author: Depth-monster

top 150/7_reverse.ts

@@ -0,0 +1,17 @@
+function reverse(x:number):number {
+    let reversed:number = 0;
+    const sign:number = x < 0 ? -1 : 1;
+    x = Math.abs(x);
+    while (x > 0) {                             //x=123; digit=0; x=12; digit=3; x=1; digit=32;
+        const digit:number = x % 10;//123             //digit = 3; digit = 2; digit = 1%10 = 1;
+        reversed = (reversed * 10) + digit;   //(0) + 3; (3*10) + 2 = 32; (32*10) + 1 = 321
+        x = Math.floor(x / 10);              //123/10 = 12.3 => 12; 12/10 = 1.2 = 1; 1/10 = 0(floor) end
+    }
+    reversed *= sign;
+    // reversed < -2147483648 ||  reversed > 2147483647
+    if (reversed < Math.pow(-2, 31) || reversed > (Math.pow(2, 31) - 1)) { 
+        return 0;
+    }
+    return reversed;
+
+}