Add function to count monobit integers

Implement a function to count monobit integers up to n by converting numbers to binary and checking for monobit conditions.

Author: jyoung2419

leetcode3/정진영/3827. Count Monobit Integers

@@ -0,0 +1,25 @@
+/**
+ * @param {number} n
+ * @return {number}
+ */
+var countMonobit = function(n) {
+    let arr = [];
+    let count = 0;
+  
+    for (let i = 0; i <= n; i++) {
+        arr.push(i.toString(2));
+    }
+
+    for (let i = 0; i < arr.length; i++) {
+        const st = arr[i].split("");
+
+        for (let j=0; j<st.length; j++){
+            if (st[0] !== st[j]){
+                count++;
+                break;
+            }
+        }
+    }
+    const ans = (arr.length - count);
+    return ans;
+};