2019-11-12

Author: JiayangWu

1192.查找集群内的「关键连接」/1192-查找集群内的「关键连接」.py

@@ -0,0 +1,41 @@
+from collections import defaultdict
+class Solution(object):
+    def criticalConnections(self, n, connections):
+        """
+        :type n: int
+        :type connections: List[List[int]]
+        :rtype: List[List[int]]
+        """
+        visited = set()
+        low = [9999999] * n
+        discover = [999999] * n
+        parent = [-1] * n
+ 
+        graph = defaultdict(list)
+        self.time = 0
+        res = []
+        for u, v in connections:
+            graph[u].append(v)
+            graph[v].append(u)
+        
+        def dfs(u):
+            visited.add(u)
+            discover[u] = self.time
+            low[u] = self.time
+            self.time += 1
+ 
+            for v in graph[u]:
+                if v not in visited:
+                    parent[v] = u
+                    dfs(v)
+                    low[u] = min(low[u], low[v])
+ 
+                    if low[v] > discover[u]:
+                        res.append([u, v])
+                elif v != parent[u]:
+                    low[u] = min(low[u], discover[v])
+                
+        for i in range(n):
+            if i not in visited:
+                dfs(i)
+        return res

1228.等差数列中缺失的数字/1228-等差数列中缺失的数字.py

@@ -0,0 +1,14 @@
+class Solution(object):
+    def missingNumber(self, arr):
+        """
+        :type arr: List[int]
+        :rtype: int
+        """
+        d = (arr[-1] - arr[0]) // len(arr)
+        
+        k = arr[0]
+        for num in arr:
+            if num != k:
+                return k
+            k += d
+        return k

1229.安排会议日程/1229-安排会议日程.py

@@ -0,0 +1,31 @@
+class Solution(object):
+    def minAvailableDuration(self, slots1, slots2, duration):
+        """
+        :type slots1: List[List[int]]
+        :type slots2: List[List[int]]
+        :type duration: int
+        :rtype: List[int]
+        """
+        slots1 = sorted(slots1, key = lambda x:x[0])
+        slots2 = sorted(slots2, key = lambda x:x[0])
+        slots = []
+        i, j = 0, 0
+        while i < len(slots1) and j < len(slots2):
+            if slots1[i][1] < slots2[j][0]:
+                i += 1
+                continue
+            elif slots1[i][0] > slots2[j][1]:
+                j += 1
+                continue
+            start = max(slots1[i][0], slots2[j][0])
+            end = min(slots1[i][1], slots2[j][1])
+            slots.append([start, end])
+            i += 1
+                
+        print(slots)
+        for start, end in slots:
+            if end - start >= duration:
+                return [start, start + duration]
+        return []
+        
+        

1230.抛掷硬币/1230-抛掷硬币.py

@@ -0,0 +1,27 @@
+class Solution(object):
+    def probabilityOfHeads(self, prob, target):
+        """
+        :type prob: List[float]
+        :type target: int
+        :rtype: float
+        """
+        dp = [0 for _ in range(len(prob) + 1)]
+        dp[1] = prob[0]
+        dp[0] = 1 - prob[0]
+        for i in range(1, len(prob)):
+            new_dp = [0 for _ in range(len(prob) + 1)]
+            for j in range(target + 1):
+                new_dp[j] = dp[j] * (1 - prob[i]) + dp[j - 1] * prob[i]
+            dp = new_dp[:]
+        return dp[target]
+    
+        # dp = [[0 for _ in range(len(prob) + 1)] for _ in range(len(prob))]
+        # # dp[i][j] 表示前i个硬币里，有j个硬币正面朝上的概率
+        # dp[0][1] = prob[0]
+        # dp[0][0] = 1 - prob[0]
+        # for i, p in enumerate(prob):
+        #     for j in range(target + 1):
+        #         if i > 0:
+        #             dp[i][j] += dp[i - 1][j] * (1 - p)
+        #             dp[i][j] += dp[i - 1][j - 1] * (p)
+        # return dp[-1][target]

1231.分享巧克力/1231-分享巧克力.py

@@ -0,0 +1,27 @@
+class Solution(object):
+    def maximizeSweetness(self, sweetness, K):
+        """
+        :type sweetness: List[int]
+        :type K: int
+        :rtype: int
+        """
+        if not K:
+            return sum(sweetness)
+        left, right = 0, sum(sweetness) // K
+        res = 0
+        while left <= right:
+            mid = (left + right) // 2
+            cnt = 0
+            tmp = 0
+            for s in sweetness:
+                if tmp + s > mid:
+                    cnt += 1
+                    tmp = 0
+                else:
+                    tmp += s
+            
+            if cnt < K + 1:
+                right = mid - 1
+            else:
+                left = mid + 1
+        return left