add 1221 ts solution

Author: JeremyXXXuuu

Problems/17-Split-a-String-in-Balanced-Strings/1221.ts

@@ -0,0 +1,14 @@
+function balancedStringSplit(s: string): number {
+    let res: number = 0;
+    let x:number = 0;
+
+    for(let i of s) {
+        if( i === 'R') x++;
+        else x--;
+
+        if(x === 0) {
+            res ++;
+        }
+    }
+    return res;
+};