20181027

Author: fay111101

src/main/java/leetcode/array/_153_FindMinimumInRotatedSortedArry.java

@@ -24,16 +24,18 @@ public int findMin(int[] nums) {
         if(nums==null||nums.length==0) return -1;
         int mid=0;
         int left=0,right=nums.length-1;
+        //控制nums[left]>=nums[right].使第一个指针永远指向第一个递增子区间，第二个指针永远指向第二个递增子区间
         while(nums[left]>=nums[right]&&left<right){
+            //第一个指针已经到达第一个子区间的末尾
             if(right-left==1){
                 mid=right;
                 break;
             }
             mid=(left+right)>>1;
             if(nums[mid]>nums[left]){
-                left=mid;
+                left=mid+1;
             }else{
-                right=mid;
+                right=mid-1;
             }
         }
 

src/main/java/leetcode/array/_15_Sum3.java

@@ -61,7 +61,6 @@ public static void main(String[] args) {
         int[] num = {-1, 0, 1, 2, -1, -4};
         int[] num1 = {0, 0, 0, 0};
         int[] num2 = {-2, 0, 1, 1, 2};
-        List<List<Integer>> result = test.threeSum(num);
         /*for(ArrayList<Integer> res:result){
             for(int a:res){
                 System.out.print(a);

…e/dfsbfsbacktracing/_126_WordLadder.java …e/dfsbfsbacktracing/_127_WordLadder.javasrc/main/java/leetcode/dfsbfsbacktracing/_126_WordLadder.java renamed to src/main/java/leetcode/dfsbfsbacktracing/_127_WordLadder.java src/main/java/leetcode/dfsbfsbacktracing/_126_WordLadder.java renamed to src/main/java/leetcode/dfsbfsbacktracing/_127_WordLadder.java

@@ -5,6 +5,7 @@
 import java.util.List;
 import java.util.Set;
 
+<<<<<<< HEAD:src/main/java/leetcode/dfsbfsbacktracing/_126_WordLadder.java
 public class _126_WordLadder {
     /**
      * bfs层次遍历的思想
@@ -14,6 +15,44 @@ public class _126_WordLadder {
      * @param dict
      * @return
      */
+=======
+/**
+ *给定两个单词（beginWord 和 endWord）和一个字典，找到从 beginWord 到 endWord 的最短转换序列的长度。转换需遵循如下规则：
+ *
+ * 每次转换只能改变一个字母。
+ * 转换过程中的中间单词必须是字典中的单词。
+ * 说明:
+ *
+ * 如果不存在这样的转换序列，返回 0。
+ * 所有单词具有相同的长度。
+ * 所有单词只由小写字母组成。
+ * 字典中不存在重复的单词。
+ * 你可以假设 beginWord 和 endWord 是非空的，且二者不相同。
+ * 示例 1:
+ *
+ * 输入:
+ * beginWord = "hit",
+ * endWord = "cog",
+ * wordList = ["hot","dot","dog","lot","log","cog"]
+ *
+ * 输出: 5
+ *
+ * 解释: 一个最短转换序列是 "hit" -> "hot" -> "dot" -> "dog" -> "cog",
+ *      返回它的长度 5。
+ * 示例 2:
+ *
+ * 输入:
+ * beginWord = "hit"
+ * endWord = "cog"
+ * wordList = ["hot","dot","dog","lot","log"]
+ *
+ * 输出: 0
+ *
+ * 解释: endWord "cog" 不在字典中，所以无法进行转换。
+ */
+public class _127_WordLadder {
+
+>>>>>>> 8d9fd232620a92e2f658ded073d959eb094bcaa1:src/main/java/leetcode/dfsbfsbacktracing/_127_WordLadder.java
     public int ladderLength(String start, String end, HashSet<String> dict) {
         if (start == null || end == null || start.length() == 0 || end.length() == 0 || start.length() != end.length())
             return 0;

…ain/java/leetcode/search/WordSearch.java …de/dfsbfsbacktracing/_79_WordSearch.javasrc/main/java/leetcode/search/WordSearch.java renamed to src/main/java/leetcode/dfsbfsbacktracing/_79_WordSearch.java src/main/java/leetcode/search/WordSearch.java renamed to src/main/java/leetcode/dfsbfsbacktracing/_79_WordSearch.java

@@ -1,4 +1,8 @@
+<<<<<<< HEAD:src/main/java/leetcode/search/WordSearch.java
 package leetcode.search;
+=======
+package leetcode.dfsbfsbacktracing;
+>>>>>>> 8d9fd232620a92e2f658ded073d959eb094bcaa1:src/main/java/leetcode/dfsbfsbacktracing/_79_WordSearch.java
 
 /**
  *  Given a 2D board and a word, find if the word exists in the grid.
@@ -17,8 +21,29 @@
  word ="ABCCED", -> returnstrue,
  word ="SEE", -> returnstrue,
  word ="ABCB", -> returnsfalse.
+ 给定一个二维网格和一个单词，找出该单词是否存在于网格中。
+
+ 单词必须按照字母顺序，通过相邻的单元格内的字母构成，其中“相邻”单元格是那些水平相邻或垂直相邻的单元格。同一个单元格内的字母不允许被重复使用。
+
+ 示例:
+
+ board =
+ [
+ ['A','B','C','E'],
+ ['S','F','C','S'],
+ ['A','D','E','E']
+ ]
+
+ 给定 word = "ABCCED", 返回 true.
+ 给定 word = "SEE", 返回 true.
+ 给定 word = "ABCB", 返回 false.
+
  */
+<<<<<<< HEAD:src/main/java/leetcode/search/WordSearch.java
 public class WordSearch {
+=======
+public class _79_WordSearch {
+>>>>>>> 8d9fd232620a92e2f658ded073d959eb094bcaa1:src/main/java/leetcode/dfsbfsbacktracing/_79_WordSearch.java
 
     public boolean exist(char[][] board, String word) {
         if(board==null||board.length==0||board[0].length==0){

…main/java/leetcode/dynamic/GrayCode.java …/java/leetcode/dpandgreedy/GrayCode.javasrc/main/java/leetcode/dynamic/GrayCode.java renamed to src/main/java/leetcode/dpandgreedy/GrayCode.java src/main/java/leetcode/dynamic/GrayCode.java renamed to src/main/java/leetcode/dpandgreedy/GrayCode.java

@@ -1,4 +1,4 @@
-package leetcode.dynamic;
+package leetcode.dpandgreedy;
 
 import java.util.ArrayList;
 

…java/leetcode/dynamic/SrambleString.java …/leetcode/dpandgreedy/SrambleString.javasrc/main/java/leetcode/dynamic/SrambleString.java renamed to src/main/java/leetcode/dpandgreedy/SrambleString.java src/main/java/leetcode/dynamic/SrambleString.java renamed to src/main/java/leetcode/dpandgreedy/SrambleString.java

@@ -1,4 +1,4 @@
-package main.java.leetcode.dynamic;
+package leetcode.dpandgreedy;
 
 /**
  * Given a string s1, we may represent it as a binary tree by partitioning it to two non-empty substrings recursively.

…a/leetcode/dynamic/WildcardMatching.java …etcode/dpandgreedy/WildcardMatching.javasrc/main/java/leetcode/dynamic/WildcardMatching.java renamed to src/main/java/leetcode/dpandgreedy/WildcardMatching.java src/main/java/leetcode/dynamic/WildcardMatching.java renamed to src/main/java/leetcode/dpandgreedy/WildcardMatching.java

@@ -1,4 +1,4 @@
-package main.java.leetcode.dynamic;
+package leetcode.dpandgreedy;
 
 /**
  *

src/main/java/leetcode/dpandgreedy/_62_UniquePaths.java

@@ -0,0 +1,47 @@
+package leetcode.dpandgreedy;
+
+/**
+ * Created by fay on 2017/12/14.
+ * A robot is located at the top-left corner of a m x n grid (marked 'Start' in the diagram below).
+ * The robot can only move either down or right at any point in time. The robot is trying to reach the bottom-right corner of the grid (marked 'Finish' in the diagram below).
+ * How many possible unique paths are there?
+ * 一个机器人位于一个 m x n 网格的左上角 （起始点在下图中标记为“Start” ）。
+ *
+ * 机器人每次只能向下或者向右移动一步。机器人试图达到网格的右下角（在下图中标记为“Finish”）。
+ *
+ * 问总共有多少条不同的路径？
+ * 说明：m 和 n 的值均不超过 100。
+ *
+ * 示例 1:
+ *
+ * 输入: m = 3, n = 2
+ * 输出: 3
+ * 解释:
+ * 从左上角开始，总共有 3 条路径可以到达右下角。
+ * 1. 向右 -> 向右 -> 向下
+ * 2. 向右 -> 向下 -> 向右
+ * 3. 向下 -> 向右 -> 向右
+ *
+ */
+public class _62_UniquePaths {
+
+    public int uniquePaths(int m, int n) {
+        if (m == 0 || n == 0) {
+            return 0;
+        }
+        int[][] dp = new int[m][n];
+        for (int i = 0; i < m; i++) {
+            dp[i][0] = 1;
+        }
+        for (int j = 0; j < n; j++) {
+            dp[0][j] = 1;
+        }
+        for (int i = 1; i < m; i++) {
+            for (int j = 1; j < n; j++) {
+                dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
+            }
+        }
+        return dp[m - 1][n - 1];
+    }
+
+}

src/main/java/leetcode/dpandgreedy/_63_UniquePaths2.java

@@ -0,0 +1,82 @@
+package leetcode.dpandgreedy;
+
+/**
+ * Created by fay on 2017/12/14.
+ *
+ Follow up for "Unique Paths":
+ Now consider if some obstacles are added to the grids. How many unique paths would there be?
+ An obstacle and empty space is marked as1and0respectively in the grid.
+ For example,
+ There is one obstacle in the middle of a 3x3 grid as illustrated below.
+ [
+ [0,0,0],
+ [0,1,0],
+ [0,0,0]
+ ]
+ 现在考虑网格中有障碍物。那么从左上角到右下角将会有多少条不同的路径？
+ 网格中的障碍物和空位置分别用 1 和 0 来表示。
+ The total number of unique paths is 2.
+ Note: m and n will be at most 100.
+ 3x3 网格的正中间有一个障碍物。
+ 从左上角到右下角一共有 2 条不同的路径：
+ 1. 向右 -> 向右 -> 向下 -> 向下
+ 2. 向下 -> 向下 -> 向右 -> 向右
+ */
+public class _63_UniquePaths2 {
+
+    public int uniquePathsWithObstacles(int[][] obstacleGrid) {
+        int n=obstacleGrid[0].length;
+        int m=obstacleGrid.length;
+        int[] dp=new int[n];
+        dp[0]=1;
+        if(obstacleGrid[0][0]==1){
+            return 0;
+        }
+        for(int i=0;i<m;i++){
+            for(int j=0;j<n;j++){
+                if(obstacleGrid[i][j]==1){
+                    dp[j]=0;
+                }else if(j>0){
+                    dp[j]+=dp[j-1];
+                }
+            }
+        }
+        return dp[n-1];
+    }
+
+    public int uniquePathsWithObstacles1(int[][] obstacleGrid) {
+        if(obstacleGrid==null || obstacleGrid.length==0)
+            return 0;
+        int m=obstacleGrid.length;
+        int n=obstacleGrid[0].length;
+        int[][] dp=new int[m][n]; //dp[i][j]表示从start到[i,j]位置不同路径条
+        // 不需要初始化，默认初始化。
+        //for(int i=0;i<m;i++)
+        // for(int j=0;j<n;j++)
+        //dp[i][j]=0;
+        for(int i=0;i<n;i++)   //第一行障碍处理
+        {
+            if(obstacleGrid[0][i]!=1)
+                dp[0][i]=1;
+            else
+                break;
+        }
+
+        for(int j=0;j<m;j++)   //第一列障碍处理
+        {
+            if(obstacleGrid[j][0]!=1)
+                dp[j][0]=1;
+            else
+                break;
+        }
+        for(int i=1;i<m;i++)
+            for(int j=1;j<n;j++)
+            {
+                if(obstacleGrid[i][j]==1)   //如果该位置是障碍，则到达该点的路径条数为0
+                    dp[i][j]=0;
+                else
+                    dp[i][j]=dp[i-1][j]+dp[i][j-1];
+            }
+        return dp[m-1][n-1];
+    }
+}

…java/leetcode/dynamic/MinmumPathSum.java …tcode/dpandgreedy/_64_MinmumPathSum.javasrc/main/java/leetcode/dynamic/MinmumPathSum.java renamed to src/main/java/leetcode/dpandgreedy/_64_MinmumPathSum.java src/main/java/leetcode/dynamic/MinmumPathSum.java renamed to src/main/java/leetcode/dpandgreedy/_64_MinmumPathSum.java

@@ -1,11 +1,26 @@
-package leetcode.dynamic;
+package leetcode.dpandgreedy;
 
 /**
- * Created by fay on 2017/12/14.
- * Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.
- Note: You can only move either down or right at any point in time.
+ 给定一个包含非负整数的 m x n 网格，请找出一条从左上角到右下角的路径，使得路径上的数字总和为最小。
+
+ 说明：每次只能向下或者向右移动一步。
+
+ 示例:
+
+ 输入:
+ [
+ [1,3,1],
+ [1,5,1],
+ [4,2,1]
+ ]
+ 输出: 7
+ 解释: 因为路径 1→3→1→1→1 的总和最小。
  */
+<<<<<<< HEAD:src/main/java/leetcode/dynamic/MinmumPathSum.java
 public class MinmumPathSum {
+=======
+public class _64_MinmumPathSum {
+>>>>>>> 8d9fd232620a92e2f658ded073d959eb094bcaa1:src/main/java/leetcode/dpandgreedy/_64_MinmumPathSum.java
 
     public int minPathSum(int[][] grid) {
         if(grid==null||grid.length==0||grid[0]==null||grid[0].length==0){