2019-05-28

Author: JiayangWu

0127.单词接龙/0127-单词接龙.py

@@ -0,0 +1,33 @@
+from collections import deque
+class Solution(object):
+    def ladderLength(self, beginWord, endWord, wordList):
+        """
+        :type beginWord: str
+        :type endWord: str
+        :type wordList: List[str]
+        :rtype: int
+        """
+        if endWord not in wordList or beginWord == endWord:
+            return 0
+        visited = set()
+        wordList = set(wordList)
+        
+        q = deque()
+        q.append([beginWord, 0])
+        
+        char = "abcdefghijklmnopqrstuvwxyz"
+        while q:
+            cur, cnt = q.popleft() #从队列里取一个出来
+            if cur == endWord: #如果刚好找到了
+                return cnt + 1
+               
+            for i in range(len(cur)):
+                for j in range(26):
+                    word = cur[:i] + char[j] + cur[i + 1:] #把26种变换可能都生成
+                    if word in wordList and word not in visited: #判断变换有没有效
+                        visited.add(word)
+                        q.append([word, cnt + 1])
+                    
+        return 0
+                    
+            

0279.完全平方数/0279-完全平方数.py

@@ -0,0 +1,29 @@
+from collections import deque
+class Solution(object):
+    def numSquares(self, n):
+        """
+        :type n: int
+        :rtype: int
+        """
+        record = []
+        for i in range(1, int(n ** 0.5) + 1):
+            record.append(i * i)
+        # print record
+        visited = set()
+        q = deque()
+        q.append([0, 0])
+        while(q):
+            m, cnt = q.popleft()
+            
+            for num in record:
+                s = m + num
+                if s == n:
+                    return cnt + 1
+                if s < n and s not in visited:
+                    visited.add(s)
+                    q.append([s, cnt + 1])
+        # return
+                    
+            
+        
+        

0370.区间加法/0370-区间加法.py

@@ -0,0 +1,18 @@
+class Solution(object):
+    def getModifiedArray(self, length, updates):
+        """
+        :type length: int
+        :type updates: List[List[int]]
+        :rtype: List[int]
+        """
+        res = [0 for _ in range(length + 1)]
+        
+        for update in updates:
+            start, end, inc = update[0], update[1], update[2]
+            res[start] += inc
+            res[end + 1] -= inc
+        
+        for i in range(1, length):
+            res[i] += res[i - 1]
+            
+        return res[:-1]

0433.最小基因变化/0433-最小基因变化.py

@@ -0,0 +1,25 @@
+from collections import deque
+class Solution(object):
+    def minMutation(self, start, end, bank):
+        bank = set(bank)
+        if end not in bank:
+            return -1
+        q = deque()
+        q.append([start, 0])
+        visited = set()
+        char = "ACGT"
+        while q: #开始BFS
+            cur, cnt = q.popleft() #取一个出来
+            if cur == end: #如果找到了
+                return cnt
+            
+            for i in range(len(cur)):
+                for j in range(4):
+                    new = cur[:i] + char[j] + cur[i + 1:] #生成从当前基因可以变换到的新基因
+                    
+                    if new in bank and new not in visited: #如果新基因有效
+                        visited.add(new)
+                        q.append([new, cnt + 1])
+                        
+        return -1
+            

0542.01矩阵/0542-01矩阵.py

@@ -0,0 +1,43 @@
+from collections import deque
+class Solution(object):
+    def updateMatrix(self, matrix):
+        """
+        :type matrix: List[List[int]]
+        :rtype: List[List[int]]
+        """
+        if not matrix or not matrix[0]:
+            return matrix
+        m, n = len(matrix), len(matrix[0])
+        res = matrix[:]
+        
+        q = deque()
+               
+        for i in range(m):
+            for j in range(n):
+                if matrix[i][j] == 0:
+                    q.append([[i, j], 0])
+
+        dx = [1, -1, 0, 0]        
+        dy = [0, 0, 1, -1]
+        visited = [[0 for _ in range(n + 1)] for _ in range(m + 1)]
+
+        while q:
+            tmp, distance = q.popleft()
+            x0, y0 = tmp[0], tmp[1]
+
+            if matrix[x0][y0] == 1:
+                res[x0][y0] = distance
+
+            for k in range(4):
+                x = x0 + dx[k]
+                y = y0 + dy[k]
+
+                if 0 <= x < m and 0 <= y < n and visited[x][y] != 1:
+                    q.append([[x, y], distance + 1])
+                    visited[x][y] = 1
+        return res
+                    
+                    
+                    
+    
+            

0752.打开转盘锁/0752-打开转盘锁.py

@@ -0,0 +1,30 @@
+from collections import deque
+class Solution(object):
+    def openLock(self, deadends, target):
+        """
+        :type deadends: List[str]
+        :type target: str
+        :rtype: int
+        """
+        deadends = set(deadends)
+        if "0000" in deadends: #如果连起点都不能走就88
+            return -1
+        
+        queue = deque()
+        queue.append(["0000", 0])
+        cnt = 0
+
+        while queue:
+            node, cnt = queue.popleft() #取一个点出来，cnt是当前走的步数
+            if node == target: #找到了
+                return cnt     
+
+            for i in range(4):
+                for j in [1, -1]:
+                    next_node = node[:i] + str((int(node[i]) + j) % 10) + node[i + 1:] 
+
+                    if next_node not in deadends: #新的点可以走而且没走过
+                        deadends.add(next_node) #避免重复
+                        queue.append([next_node, cnt + 1])
+
+        return -1