2020-08-27

Author: JiayangWu

0342.4的幂/0342-4的幂.py

@@ -1 +1,12 @@
-None
+class Solution(object):
+    def isPowerOfFour(self, num):
+        """
+        :type num: int
+        :rtype: bool
+        """
+        while num >= 4:
+            if num % 4:
+                return False
+            num //= 4
+
+        return num == 1

1556.千位分隔数/1556-千位分隔数.py

@@ -1 +1,13 @@
-None
+class Solution(object):
+    def thousandSeparator(self, n):
+        """
+        :type n: int
+        :rtype: str
+        """
+        s = str(n)[::-1]
+        res = ""
+        for i in range(len(s)):
+            res += s[i]
+            if i % 3 == 2 and i != len(s) - 1:
+                res += "."
+        return res[::-1] 

1558.得到目标数组的最少函数调用次数/1558-得到目标数组的最少函数调用次数.py

@@ -1 +1,12 @@
-None
+class Solution(object):
+    def minOperations(self, nums):
+        """
+        :type nums: List[int]
+        :rtype: int
+        """
+        res = 0
+        for num in nums:
+            res += bin(num).count("1")
+
+        res += len(bin(max(nums))[2:]) - 1
+        return res

1559.二维网格图中探测环/1559-二维网格图中探测环.py

@@ -1 +1,54 @@
-None
+class Solution(object):
+    def containsCycle(self, grid):
+        """
+        :type grid: List[List[str]]
+        :rtype: bool
+        """
+        dx = [1, -1, 0, 0]
+        dy = [0, 0, 1, -1]
+        ufs = UnionFindSet(grid)
+        m, n = len(grid), len(grid[0])
+        for i in range(m):
+            for j in range(n):
+                for next_i, next_j in [(i - 1, j), (i, j - 1)]:
+                    if 0 <= next_i < m and 0 <= next_j < n and grid[next_i][next_j] == grid[i][j]:
+                        if ufs.find(i * n + j) == ufs.find(next_i * n + next_j):
+                            return True
+                        else:
+                            ufs.union(i * n + j, next_i * n + next_j)                 
+        return False
+        
+class UnionFindSet(object):
+    def __init__(self, grid):
+        m, n = len(grid), len(grid[0])
+        self.roots = [-1 for i in range(m*n)]
+        self.rank = [0 for i in range(m*n)]
+        self.count = 0
+        
+        for i in range(m):
+            for j in range(n):
+                self.roots[i * n + j] = i * n + j
+                self.count += 1
+        
+    def find(self, member):
+        tmp = []
+        while member != self.roots[member]:
+            tmp.append(member)
+            member = self.roots[member]
+        for root in tmp:
+            self.roots[root] = member
+        return member
+        
+    def union(self, p, q):
+        parentP = self.find(p)
+        parentQ = self.find(q)
+        if parentP != parentQ:
+            if self.rank[parentP] > self.rank[parentQ]:
+                self.roots[parentQ] = parentP
+            elif self.rank[parentP] < self.rank[parentQ]:
+                self.roots[parentP] = parentQ
+            else:
+                self.roots[parentQ] = parentP
+                self.rank[parentP] -= 1
+            self.count -= 1
+