[sangbeenmoon] WEEK 09 Solutions

maximum-product-subarray/sangbeenmoon.py

@@ -0,0 +1,17 @@
+class Solution:
+    def maxProduct(self, nums: List[int]) -> int:
+        min_val = nums[0]
+        max_val = nums[0]
+        answer = max_val
+
+        for i in range(1, len(nums)):
+            target = nums[i]
+            prev_max_val = max_val
+
+            max_val = max(max_val * target, min_val * target, target)
+            min_val = min(prev_max_val * target, min_val * target, target)
+            answer = max(answer, max_val)
+
+        return answer
+
+

pacific-atlantic-water-flow/sangbeenmoon.py

@@ -0,0 +1,42 @@
+class Solution:
+    def pacificAtlantic(self, heights: List[List[int]]) -> List[List[int]]:
+
+        m,n = len(heights), len(heights[0])
+        pacific = [[False] * n for _ in range(m)]
+        atlantic = [[False] * n for _ in range(m)]
+
+        visited = [[False] * n for _ in range(m)]
+
+        dx = [0,0,-1,1]
+        dy = [-1,1,0,0]
+
+
+        def go(root_x:int, root_y:int, xx:int, yy:int):
+
+            for d in range(4):
+                nx = xx + dx[d]
+                ny = yy + dy[d]
+
+                if ny == -1 or nx == -1:
+                    pacific[root_y][root_x] = True
+                if ny == m or nx == n:
+                    atlantic[root_y][root_x] = True
+
+                if 0 <= ny and ny < m and 0 <= nx and nx < n:
+                    if heights[ny][nx] <= heights[yy][xx] and not visited[ny][nx]:
+                        visited[ny][nx] = True
+                        go(root_x, root_y, nx, ny)
+
+        for y in range(m):
+            for x in range(n):
+                visited = [[False] * n for _ in range(m)]
+                go(x,y,x,y)
+
+        answer = []
+
+        for y in range(m):
+            for x in range(n):
+                if pacific[y][x] and atlantic[y][x]:
+                    answer.append([y,x])
+
+        return answer