diff --git a/coin-change/crumbs22.cpp b/coin-change/crumbs22.cpp
new file mode 100644
index 000000000..15f124384
--- /dev/null
+++ b/coin-change/crumbs22.cpp
@@ -0,0 +1,36 @@
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+/*
+	- dp[i]: 금액 i를 만드는 최소 코인수
+	- 초기값
+		- dp[0] = 0
+		- 그 외에는 amount + 1 (도달할 수 없는 값)으로 초기화
+	- 현재 금액 i를 만들기 위해서
+		이전 금액인 i - c를 만들고, 거기에 코인 c를 더 썼을 때 최소값을 갱신함
+	예시) coins = [1, 2, 5], i = 3일 때
+			c = 1 ->  3 >= 1 이므로 dp[3] = min(dp[3], dp[2] + 1) 갱신
+			c = 2 ->  3 >= 2 이므로 dp[3] = min(dp[3], dp[1] + 1) 갱신
+			c = 5 ->  3 < 5 이므로 건너뜀
+		=> i - c가 음수면 배열 범위를 벗어나므로 i >= c일때만 연산산
+*/
+class Solution {
+public:
+	int coinChange(vector<int>& coins, int amount) {
+		// dp 테이블 초기화
+		vector<int> dp(amount + 1, amount + 1);
+		dp[0] = 0;
+
+		// bottom up 연산
+		for (int i = 1; i <= amount; ++i) {
+			for (int c : coins) {
+				if (i >= c) {
+					dp[i] = min(dp[i], dp[i - c] + 1);
+				}
+			}
+		}
+
+		return (dp[amount] > amount) ? -1 : dp[amount];
+	}
+};
diff --git a/find-minimum-in-rotated-sorted-array/crumbs22.cpp b/find-minimum-in-rotated-sorted-array/crumbs22.cpp
new file mode 100644
index 000000000..7dc865fd3
--- /dev/null
+++ b/find-minimum-in-rotated-sorted-array/crumbs22.cpp
@@ -0,0 +1,32 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+/*
+	O(logn)으로 풀어라
+		- 이진 탐색 느낌
+		- mid값과 오른쪽 끝을 비교,
+			- mid > 오른쪽 끝 : 최소는 오른쪽에
+			- mid <= 오른쪽 끝 : 최소는 mid 포함 왼쪽에
+*/
+
+class Solution {
+	public:
+		int findMin(vector<int>& nums) {
+			int left = 0;
+			int right = nums.size() - 1;
+
+			while (left < right) {
+				int mid =  left + (right - left) / 2;
+
+				if (nums[mid] > nums[right]) {
+					left = mid + 1;
+				}
+				else {
+					right = mid;
+				}
+			}
+			return (nums[left]);
+		}
+	};
diff --git a/maximum-depth-of-binary-tree/crumbs22.cpp b/maximum-depth-of-binary-tree/crumbs22.cpp
new file mode 100644
index 000000000..603b75eae
--- /dev/null
+++ b/maximum-depth-of-binary-tree/crumbs22.cpp
@@ -0,0 +1,19 @@
+#include <algorithm>
+
+struct TreeNode {
+    int val;
+    TreeNode *left;
+    TreeNode *right;
+    TreeNode() : val(0), left(nullptr), right(nullptr) {}
+    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
+    TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
+};
+
+class Solution {
+	public:
+		int maxDepth(TreeNode* root) {
+			if (!root)
+				return (0);
+			return (std::max(maxDepth(root->left), maxDepth(root->right)) + 1);
+		}
+	};
diff --git a/merge-two-sorted-lists/crumbs22.cpp b/merge-two-sorted-lists/crumbs22.cpp
new file mode 100644
index 000000000..291332e9b
--- /dev/null
+++ b/merge-two-sorted-lists/crumbs22.cpp
@@ -0,0 +1,44 @@
+#include <iostream>
+
+using namespace std;
+
+struct ListNode {
+    int val;
+    ListNode *next;
+    ListNode() : val(0), next(nullptr) {}
+    ListNode(int x) : val(x), next(nullptr) {}
+    ListNode(int x, ListNode *next) : val(x), next(next) {}
+};
+
+class Solution {
+    public:
+        ListNode* mergeTwoLists(ListNode* list1, ListNode* list2) {
+            if (!list1)
+                return (list2);
+            if (!list2)
+                return (list1);
+    
+            ListNode ans_head = ListNode();
+            ListNode* tmp = &ans_head;
+    
+            while (list1 && list2) {
+                if (list1->val <= list2->val) {
+                    tmp->next = list1;
+                    list1 = list1->next;
+                    tmp = tmp->next;
+                }
+                else {
+                    tmp->next = list2;
+                    list2 = list2->next;
+                    tmp = tmp->next;
+                }
+            }
+            if (list1) {
+                tmp->next = list1;
+            }
+            else if (list2) {
+                tmp->next = list2;
+            }
+            return (ans_head.next);
+        }
+    };
diff --git a/word-search/crumbs22.cpp b/word-search/crumbs22.cpp
new file mode 100644
index 000000000..bb0b874c8
--- /dev/null
+++ b/word-search/crumbs22.cpp
@@ -0,0 +1,41 @@
+#include <vector>
+#include <string>
+
+using namespace std;
+
+class Solution {
+public:
+    bool exist(vector<vector<char>>& board, string word) {
+		// 단어 시작점을 탐색, 시작점 찾으면 dfs 시작하고 마지막 단어까지 도달 가능할 때 true 반환
+        for (int i = 0; i < board.size(); i++) {
+			for (int j = 0;  j < board[0].size(); j++) {
+				if (board[i][j] == word[0] && dfs(board, i, j, 0, word)) {
+					return (true);
+				}
+			}
+		}
+		return (false);
+    }
+	bool dfs(vector<vector<char>>& board, int i, int j, int idx, string& word)  {
+		if (idx == word.size())
+			return (true);
+		if (i < 0 || i >= board.size() || \
+			j < 0 || j >= board[0].size() || \
+			board[i][j] != word[idx]) {
+				return (false);
+		}
+
+		char tmp = board[i][j];
+
+		// 방문 표시
+		board[i][j] = '1';
+
+		// 4방향으로 탐색
+		bool found = dfs(board, i + 1, j, idx + 1, word) || dfs(board, i - 1, j, idx + 1, word) || \
+					dfs(board, i, j + 1, idx + 1, word) || dfs(board, i, j - 1, idx + 1, word);
+		
+		// 다른 경로 탐색을 위해서 방문 표시를 원래대로 복원
+		board[i][j] = tmp;
+		return (found);
+	}
+};