Week 4

Author: 8804who

coin-change/8804who.py

@@ -0,0 +1,13 @@
+class Solution:
+    def coinChange(self, coins: List[int], amount: int) -> int:
+        dp = [1e9] * (amount+1)
+        dp[0] = 0
+        
+        for i in range(1, amount+1):
+            for coin in coins:
+                if i-coin>=0:
+                    if dp[i-coin]+1<dp[i]:
+                        dp[i]=dp[i-coin]+1
+        
+        return -1 if dp[amount]==1e9 else dp[amount]
+    

find-minimum-in-rotated-sorted-array/8804who.py

@@ -0,0 +1,14 @@
+class Solution:
+    def findMin(self, nums: List[int]) -> int:
+        left = 0
+        right = len(nums)-1
+        while True:
+            mid = (left+right)//2
+            if nums[left] > nums[right]:
+                if nums[left] > nums[mid]:
+                    right = mid
+                else:
+                    left = mid+1
+            else:
+                return nums[left]
+            

word-search/8804who.py

@@ -0,0 +1,31 @@
+class Solution:
+    def exist(self, board: List[List[str]], word: str) -> bool:
+        moves = [[-1, 0], [1, 0], [0, -1], [0, 1]]
+        max_y, max_x = len(board)-1, len(board[0])-1
+
+        visited = [[False for _ in range(len(board[0]))] for _ in range(len(board))]
+
+
+        def dfs(y, x, idx):
+            if idx == len(word):
+                return True
+            for move in moves:
+                moved_y, moved_x = y+move[0], x+move[1]
+                if max_y >= moved_y  and moved_y >= 0 and max_x >= moved_x and moved_x >= 0:
+                    if board[moved_y][moved_x] == word[idx] and not visited[moved_y][moved_x]:
+                        visited[moved_y][moved_x] = True
+                        if dfs(moved_y, moved_x, idx+1):
+                            return True
+                        visited[moved_y][moved_x] = False
+
+
+        for y in range(max_y+1):
+            for x in range(max_x+1):
+                if board[y][x] == word[0]:
+                    visited[y][x] = True
+                    if dfs(y, x, 1):
+                        return True
+                    visited[y][x] = False
+        
+        return False
+