From 70307dc4ccab73a779e44f82e9d3a8d7fe8f71e7 Mon Sep 17 00:00:00 2001
From: eunice-hong <dev@eunice-hong.com>
Date: Mon, 21 Apr 2025 22:31:11 +0900
Subject: [PATCH 1/6] solve: W04 merge two sorted list

---
 merge-two-sorted-lists/eunice-hong.ts | 34 +++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 merge-two-sorted-lists/eunice-hong.ts

diff --git a/merge-two-sorted-lists/eunice-hong.ts b/merge-two-sorted-lists/eunice-hong.ts
new file mode 100644
index 000000000..7dd1fde23
--- /dev/null
+++ b/merge-two-sorted-lists/eunice-hong.ts
@@ -0,0 +1,34 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+/**
+ * 
+ * Time Complexity: O(n + m)
+ * Space Complexity: O(n + m)
+ */
+function mergeTwoLists(list1: ListNode | null, list2: ListNode | null): ListNode | null {
+    if (!list1 && !list2) {
+        // both lists are empty
+        return null
+    } else if (!list1) {
+        // list1 is empty
+        return list2
+    } else if (!list2) {
+        // list2 is empty
+        return list1
+    } else if (list1.val <= list2.val) {
+        // list1's current node is smaller
+        return new ListNode(list1.val, mergeTwoLists(list1.next, list2))
+    } else {
+        // list2's current node is smaller
+        return new ListNode(list2.val, mergeTwoLists(list1, list2.next))
+    }
+};
\ No newline at end of file

From 90ecae0b37070107b7505dd77b1a6b1bbcce30d1 Mon Sep 17 00:00:00 2001
From: eunice-hong <dev@eunice-hong.com>
Date: Mon, 21 Apr 2025 22:35:46 +0900
Subject: [PATCH 2/6] solve: W04 maximum depth of binary tree

---
 maximum-depth-of-binary-tree/eunice-hong.ts | 31 +++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 maximum-depth-of-binary-tree/eunice-hong.ts

diff --git a/maximum-depth-of-binary-tree/eunice-hong.ts b/maximum-depth-of-binary-tree/eunice-hong.ts
new file mode 100644
index 000000000..af38078d7
--- /dev/null
+++ b/maximum-depth-of-binary-tree/eunice-hong.ts
@@ -0,0 +1,31 @@
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+/**
+ * 
+ * Time Complexity: O(n)
+ * Space Complexity: O(n)
+ */
+function maxDepth(root: TreeNode | null): number {
+    if (!root) {
+        // tree is empty
+        return 0
+    } else if (!root.left && !root.right) {
+        // tree has no children
+        return 1
+    } else {
+        // tree has at least one child
+        return 1 + Math.max(maxDepth(root.left), maxDepth(root.right))
+    }
+};
\ No newline at end of file

From ea4023be533ad2419f64a737fba6c5dcdc1276d2 Mon Sep 17 00:00:00 2001
From: eunice-hong <dev@eunice-hong.com>
Date: Mon, 21 Apr 2025 22:47:55 +0900
Subject: [PATCH 3/6] solve: W04 find minimum in rotated sorted array

---
 .../eunice-hong.ts                                | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 find-minimum-in-rotated-sorted-array/eunice-hong.ts

diff --git a/find-minimum-in-rotated-sorted-array/eunice-hong.ts b/find-minimum-in-rotated-sorted-array/eunice-hong.ts
new file mode 100644
index 000000000..dc4cff965
--- /dev/null
+++ b/find-minimum-in-rotated-sorted-array/eunice-hong.ts
@@ -0,0 +1,15 @@
+
+/**
+ * 
+ * Time Complexity: O(n)
+ * Space Complexity: O(1)
+ */
+function findMin(nums: number[]): number {
+    let index = 0;
+    // find the index of where the value is greater than the next value
+    while (nums[index] < nums[(index + 1) % nums.length]) {
+      index++;
+    }
+    // return the next value
+    return nums[(index + 1) % nums.length]
+};
\ No newline at end of file

From 3d1166a90127bc22e658b41cd54fcf5bbd68a735 Mon Sep 17 00:00:00 2001
From: eunice-hong <dev@eunice-hong.com>
Date: Fri, 25 Apr 2025 22:12:46 +0900
Subject: [PATCH 4/6] solve: W04 coin change

---
 coin-change/eunice-hong.ts | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 coin-change/eunice-hong.ts

diff --git a/coin-change/eunice-hong.ts b/coin-change/eunice-hong.ts
new file mode 100644
index 000000000..0bc05845c
--- /dev/null
+++ b/coin-change/eunice-hong.ts
@@ -0,0 +1,24 @@
+
+/**
+ * 
+ * Time Complexity: O(n * amount)
+ * Space Complexity: O(amount)
+ */
+function coinChange(coins: number[], amount: number): number {
+  // Initialize dp array with Infinity
+  const dp = new Array(amount + 1).fill(Infinity);
+  // Base case: 0 coins needed to make amount 0
+  dp[0] = 0;
+
+  // Iterate through each coin
+  for (let coin of coins) {
+    // Update dp array for each amount from coin to amount
+    for (let i = coin; i <= amount; i++) {
+      // Choose the minimum between current dp[i] and dp[i - coin] + 1
+      dp[i] = Math.min(dp[i], dp[i - coin] + 1);
+    }
+  }
+
+  // If dp[amount] is still Infinity, it means it's not possible to make the amount
+  return dp[amount] === Infinity ? -1 : dp[amount];
+}
\ No newline at end of file

From 9e2396dfce7216ce9aa0fff0653f092442b583bb Mon Sep 17 00:00:00 2001
From: eunice-hong <dev@eunice-hong.com>
Date: Fri, 25 Apr 2025 22:24:58 +0900
Subject: [PATCH 5/6] solve: W04 word search

---
 word-search/eunice-hong.ts | 45 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 word-search/eunice-hong.ts

diff --git a/word-search/eunice-hong.ts b/word-search/eunice-hong.ts
new file mode 100644
index 000000000..5922238dc
--- /dev/null
+++ b/word-search/eunice-hong.ts
@@ -0,0 +1,45 @@
+
+/**
+ * Time Complexity: O(m * n * 4^k)
+ * Space Complexity: O(m * n)
+ */
+function exist(board: string[][], word: string): boolean {
+  // Initialize the board dimensions
+  const m = board.length;
+  const n = board[0].length;
+
+  const dfs = (i: number, j: number, index: number): boolean => {
+    // If we've matched all characters, return true
+    if (index === word.length) return true;
+    // If out of bounds or current character doesn't match, return false
+    if (i < 0 || i >= m || j < 0 || j >= n || board[i][j] !== word[index]) return false;
+
+    // Temporarily mark the current cell as visited
+    const temp = board[i][j];
+    board[i][j] = '#';
+
+    // Explore all four possible directions
+    const found =
+      dfs(i + 1, j, index + 1) ||
+      dfs(i - 1, j, index + 1) ||
+      dfs(i, j + 1, index + 1) ||
+      dfs(i, j - 1, index + 1);
+
+    // Unmark the current cell (backtracking)
+    board[i][j] = temp;
+
+    // Return true if we found the word
+    return found;
+  };
+
+  // Iterate through each cell in the board
+  for (let i = 0; i < m; i++) {
+    for (let j = 0; j < n; j++) {
+      // Start DFS from each cell
+      if (dfs(i, j, 0)) return true;
+    }
+  }
+
+  // If we didn't find the word, return false
+  return false;
+}
\ No newline at end of file

From 4c9c3c1e891d38174a5a1a513b68693aa0864bfb Mon Sep 17 00:00:00 2001
From: eunice-hong <dev@eunice-hong.com>
Date: Fri, 25 Apr 2025 22:28:11 +0900
Subject: [PATCH 6/6] chore: Add missing newline at end of file in multiple
 solution files

---
 coin-change/eunice-hong.ts                          | 2 +-
 find-minimum-in-rotated-sorted-array/eunice-hong.ts | 2 +-
 maximum-depth-of-binary-tree/eunice-hong.ts         | 2 +-
 merge-two-sorted-lists/eunice-hong.ts               | 2 +-
 word-search/eunice-hong.ts                          | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/coin-change/eunice-hong.ts b/coin-change/eunice-hong.ts
index 0bc05845c..3d9cabb03 100644
--- a/coin-change/eunice-hong.ts
+++ b/coin-change/eunice-hong.ts
@@ -21,4 +21,4 @@ function coinChange(coins: number[], amount: number): number {
 
   // If dp[amount] is still Infinity, it means it's not possible to make the amount
   return dp[amount] === Infinity ? -1 : dp[amount];
-}
\ No newline at end of file
+}
diff --git a/find-minimum-in-rotated-sorted-array/eunice-hong.ts b/find-minimum-in-rotated-sorted-array/eunice-hong.ts
index dc4cff965..1e5f643ee 100644
--- a/find-minimum-in-rotated-sorted-array/eunice-hong.ts
+++ b/find-minimum-in-rotated-sorted-array/eunice-hong.ts
@@ -12,4 +12,4 @@ function findMin(nums: number[]): number {
     }
     // return the next value
     return nums[(index + 1) % nums.length]
-};
\ No newline at end of file
+};
diff --git a/maximum-depth-of-binary-tree/eunice-hong.ts b/maximum-depth-of-binary-tree/eunice-hong.ts
index af38078d7..9cf35881c 100644
--- a/maximum-depth-of-binary-tree/eunice-hong.ts
+++ b/maximum-depth-of-binary-tree/eunice-hong.ts
@@ -28,4 +28,4 @@ function maxDepth(root: TreeNode | null): number {
         // tree has at least one child
         return 1 + Math.max(maxDepth(root.left), maxDepth(root.right))
     }
-};
\ No newline at end of file
+};
diff --git a/merge-two-sorted-lists/eunice-hong.ts b/merge-two-sorted-lists/eunice-hong.ts
index 7dd1fde23..f2535fbbc 100644
--- a/merge-two-sorted-lists/eunice-hong.ts
+++ b/merge-two-sorted-lists/eunice-hong.ts
@@ -31,4 +31,4 @@ function mergeTwoLists(list1: ListNode | null, list2: ListNode | null): ListNode
         // list2's current node is smaller
         return new ListNode(list2.val, mergeTwoLists(list1, list2.next))
     }
-};
\ No newline at end of file
+};
diff --git a/word-search/eunice-hong.ts b/word-search/eunice-hong.ts
index 5922238dc..143076b94 100644
--- a/word-search/eunice-hong.ts
+++ b/word-search/eunice-hong.ts
@@ -42,4 +42,4 @@ function exist(board: string[][], word: string): boolean {
 
   // If we didn't find the word, return false
   return false;
-}
\ No newline at end of file
+}