diff --git a/contains-duplicate/aa601.c b/contains-duplicate/aa601.c
new file mode 100644
index 000000000..c0c3c52a1
--- /dev/null
+++ b/contains-duplicate/aa601.c
@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+void	merge(int *nums, int left, int mid, int right)
+{
+	int	i;
+	int	j;
+	int	k;
+	int	leftArr[mid - left + 1];
+	int	rightArr[right - mid];
+
+	i = -1;
+	while (++i < mid - left + 1) // 왼쪽 분할된 부분 넣기
+		leftArr[i] = nums[left + i];
+	i = -1;
+	while (++i < right - mid) // 오른쪽 분할된 부분 넣기
+		rightArr[i] = nums[mid + i + 1];
+	i = 0;
+	j = 0;
+	k = left; // **** nums배열인덱스 => left부터 시작
+	// 나누어진 배열끼리 비교해서 nums배열 재배치
+	while ((i < mid - left + 1) && (j < right - mid)) {
+		if (leftArr[i] <= rightArr[j])
+			nums[k] = leftArr[i++];
+		else
+			nums[k] = rightArr[j++];
+		++k;
+	}
+	while (i < mid - left + 1) // left배열 남아있으면 마저 삽입
+		nums[k++] = leftArr[i++];
+	while (j < right - mid) // right배열 남아있으면 마저 삽입
+		nums[k++] = rightArr[j++];
+}
+
+void	mergeSort(int *nums, int left, int right) {
+	int	mid;
+
+	if (left < right)
+	{
+		mid = (left + right) / 2;
+		mergeSort(nums, left, mid); // 왼쪽분할
+		mergeSort(nums, mid + 1, right); // 오른쪽분할
+		merge(nums, left, mid, right);
+	}
+}
+
+bool containsDuplicate(int* nums, int numsSize) {
+	int	i;
+
+	mergeSort(nums, 0, numsSize - 1);
+	i = -1;
+	while (++i + 1 < numsSize) {
+		if (nums[i] == nums[i + 1])
+			return (true);
+	}
+	return (false);
+}
+
+
+