diff --git a/merge-intervals/robinyoon-dev.js b/merge-intervals/robinyoon-dev.js
new file mode 100644
index 0000000000..f459c121d5
--- /dev/null
+++ b/merge-intervals/robinyoon-dev.js
@@ -0,0 +1,40 @@
+/**
+ * @param {number[][]} intervals
+ * @return {number[][]}
+ */
+var merge = function (intervals) {
+
+    let result = [];
+
+    let sortedIntervals = intervals.toSorted((a, b) => a[0] - b[0]);
+
+    for (let interval of sortedIntervals) {
+
+        if (result.length == 0) {
+            result.push(interval);
+            continue;
+        }
+
+        let intervalStart = interval[0];
+        let intervalEnd = interval[1];
+
+        let lastItemInResult = result[result.length - 1];
+
+        let start = lastItemInResult[0];
+        let end = lastItemInResult[1];
+
+        let isIntervalStartInRange = intervalStart >= start && intervalStart <= end;
+
+        if (isIntervalStartInRange) {
+            if (intervalEnd > end) {
+                result[result.length - 1][1] = intervalEnd;
+            }
+        } else {
+            result.push(interval);
+        }
+
+    }
+
+    return result;
+
+};
diff --git a/missing-number/robinyoon-dev.js b/missing-number/robinyoon-dev.js
new file mode 100644
index 0000000000..ed68aaa5a2
--- /dev/null
+++ b/missing-number/robinyoon-dev.js
@@ -0,0 +1,17 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var missingNumber = function (nums) {
+
+    let n = nums.length + 1;
+    let sortedNums = nums.sort((a, b) => a - b);
+
+    for (let i = 0; i < n; i++) {
+        if (sortedNums[i] === i) {
+            continue;
+        } else {
+            return i;
+        }
+    }
+};