2020-07-12

Author: JiayangWu

.DS_Store

@@ -0,0 +1,20 @@
+class Solution(object):
+    def calculateMinimumHP(self, dungeon):
+        """
+        :type dungeon: List[List[int]]
+        :rtype: int
+        """
+        if len(dungeon[0])==0:
+            return 1
+        dungeon[-1][-1] = max(1,1-dungeon[-1][-1])
+        # 边界
+        for i in range(len(dungeon)-2,-1,-1):
+            dungeon[i][-1] = max(1,dungeon[i+1][-1]-dungeon[i][-1])
+        for j in range(len(dungeon[0])-2,-1,-1):
+            dungeon[-1][j] = max(1,dungeon[-1][j+1]-dungeon[-1][j])
+
+        for i in range(len(dungeon)-2,-1,-1):
+            for j in range(len(dungeon[0])-2,-1,-1):
+                dungeon[i][j] = max(1,min(dungeon[i][j+1]-dungeon[i][j],dungeon[i+1][j]-dungeon[i][j]))
+        # print(dungeon)
+        return dungeon[0][0]

0174.地下城游戏/0174-地下城游戏.py

@@ -1,29 +1,33 @@
 class Solution(object):
-    def numIslands(self, grid):
+    def numIslands(self, M):
         """
         :type grid: List[List[str]]
         :rtype: int
         """
-        if not grid or not grid[0]:
+        if not M or not M[0]:
             return 0
-        m, n = len(grid), len(grid[0])
+        m, n = len(M), len(M[0])
+        visited = [[0 for j in range(n)] for i in range(m)]
+        # print visited
         dx = [1, -1, 0, 0]
         dy = [0, 0, 1, -1]
-        def dfs(x, y):
-            for k in range(4):
-                xx = x + dx[k]
-                yy = y + dy[k]
-                
-                if 0 <= xx < m and 0 <= yy < n and grid[xx][yy] == "1":
-                    grid[xx][yy] = "0"
-                    dfs(xx, yy)
-        
-        
         res = 0
+        
+        def dfs(x0, y0):
+            for k in range(4):
+                x = x0 + dx[k]
+                y = y0 + dy[k]
+                # print x, y
+                if 0<= x < m and 0 <= y < n and M[x][y] == '1' and visited[x][y] ==0:
+                    visited[x][y] = 1
+                    dfs(x, y)
+
         for i in range(m):
             for j in range(n):
-                if grid[i][j] == "1":
-                    grid[i][j] = "0"
-                    dfs(i, j)
+                if M[i][j] == '1' and visited[i][j] == 0:
                     res += 1
+                    visited[i][j] = 1
+                    dfs(i, j)
+                    # print visited
+                    
         return res

0200.岛屿数量/0200-岛屿数量.py

@@ -11,7 +11,6 @@ def countSmaller(self, nums):
         :type nums: List[int]
         :rtype: List[int]
         """
-        
         # 从左往右处理，右边是未知的，所以不好弄
         # 从右往左处理，则对于每个数，其右边的数都已知
         res = [0 for _ in nums]
@@ -21,15 +20,13 @@ def countSmaller(self, nums):
         return res[::-1]
 
     def insert(self, root, val, i, res):
-        if not root:
+        if not root: #如果当前root为空
             root = TreeNode(val)
-        elif root.val >= val:
+        elif root.val >= val: # 如果应该插入左子树
             root.left_subtree_cnt += 1
             root.left = self.insert(root.left, val, i, res)
-        elif root.val < val:
-            res[i] += root.left_subtree_cnt + 1
+        elif root.val < val: # 如果应该插入右子树
+            res[i] += root.left_subtree_cnt + 1 # 1 代表当前root
             root.right = self.insert(root.right, val, i, res)
 
-        return root
-            
-            
+        return root

0315.计算右侧小于当前元素的个数/0315-计算右侧小于当前元素的个数.py

@@ -5,12 +5,11 @@ def intersect(self, nums1, nums2):
         :type nums2: List[int]
         :rtype: List[int]
         """
+        from collections import Counter
+        dic1 = Counter(nums1)
+        dic2 = Counter(nums2)
+        
         res = []
-        for i in range(0,len(nums1)):
-            if nums1[i] in nums2:
-                nums2.remove(nums1[i])
-                # print nums1,nums2
-                res.append(nums1[i])
-                
-            # print nums1,nums2,res
+        for key, val in dic1.items():
+            res += [key] * min(val, dic2[key])
         return res

0350.两个数组的交集II/0350-两个数组的交集II.py

@@ -7,13 +7,11 @@ def minDifference(self, nums):
         if len(nums) <= 4:
             return 0
         nums.sort()
-
+        # print nums
         # 1. 去前三个
         res = nums[-1] - nums[3]
         # 2. 去前两个和最后一个
         res = min(res, nums[-2] - nums[2])
-        # 3. 去第一个和最后两个
         res = min(res, nums[-3] - nums[1])
-        # 4. 去最后三个
         res = min(res, nums[-4] - nums[0])
         return res

1509.三次操作后最大值与最小值的最小差/1509-三次操作后最大值与最小值的最小差.py

@@ -0,0 +1,12 @@
+class Solution(object):
+    def waysToChange(self, n):
+        """
+        :type n: int
+        :rtype: int
+        """
+        coin = [1, 5, 10, 25]
+        dp = [1] + [0] * n
+        for c in coin:
+            for i in range(c, n + 1):
+                dp[i] += dp[i - c]
+        return dp[-1] % (10**9 + 7)