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);
+}
+
+
+
diff --git a/house-robber/aa601.c b/house-robber/aa601.c
new file mode 100644
index 000000000..3e3ef85a8
--- /dev/null
+++ b/house-robber/aa601.c
@@ -0,0 +1,40 @@
+int rob(int* nums, int numsSize) {
+	int	*dp;
+	int	max;
+	int	i;
+	int	j;
+
+	// dp에 nums 복사
+	dp = malloc(sizeof(int) * numsSize);
+	if (!dp)
+		return (0);
+	i = -1;
+	while (++i < numsSize) {
+		dp[i] = nums[i];
+    }
+	
+	// dp 시작
+	i = 0;
+	j = 0;
+	while (++i < numsSize) {
+		j = 0;
+		max = dp[i];
+		while (j + 1 < i) {
+			if (max < dp[i] + dp[j])
+				max = dp[i] + dp[j];
+			++j;
+		}
+		dp[i] = max;
+	}
+
+	// dp 배열의 최종 max값 리턴
+	i = -1;
+	max = dp[0];
+	while (++i < numsSize) {
+		if (max < dp[i])
+			max = dp[i];
+	}
+    free(dp);
+	return (max);
+}
+
diff --git a/valid-palindrome/aa601.c b/valid-palindrome/aa601.c
new file mode 100644
index 000000000..83dd4dab3
--- /dev/null
+++ b/valid-palindrome/aa601.c
@@ -0,0 +1,27 @@
+bool isPalindrome(char* s) {
+	int		i;
+	int		j;
+	int		size;
+	char	tmp;
+	int		flag;
+
+	i = 0;
+	size = strlen(s);
+	j = size - 1;
+	flag = 1;
+	while (i < j) {
+		if (!isalnum(s[i])) {
+			++i;
+			continue ;
+		}
+		else if (!isalnum(s[j])) {
+			--j;
+			continue ;
+		}
+		if (tolower(s[i++]) != tolower(s[j--])) {
+			flag = 0;
+			break ;
+		}
+	}
+	return (flag);
+}