代码更新

Author: h2pl

src/BinSearch/Sqrt.java

@@ -1,5 +1,5 @@
 package BinSearch;
-import java.lang.Math.*;
+
 /**
  * Created by 周杰伦 on 2018/3/16.
  */

src/BinSearch/arrangeCoins.java

@@ -3,7 +3,7 @@
 /**
  * Created by 周杰伦 on 2018/3/16.
  */
-public class arrangeCoins {
+public class    arrangeCoins {
     public int arrangeCoins(int n) {
         if (n <= 1) {
             return n;

src/BinSearch/singleNonDuplicate.java

@@ -4,7 +4,11 @@
  * Created by 周杰伦 on 2018/3/16.
  */
 public class singleNonDuplicate {
-    public int singleNonDuplicate(int[] nums) {
+    public static void main(String[] args) {
+        int []num = {1,1,2,3,3,4,4,8,8};
+        System.out.println(singleNonDuplicate(num));
+    }
+    public int singleNonDuplicate1(int[] nums) {
         // binary search
         int n=nums.length, lo=0, hi=n/2;
         while (lo < hi) {
@@ -14,4 +18,30 @@ public int singleNonDuplicate(int[] nums) {
         }
         return nums[2*lo];
     }
+    public static int singleNonDuplicate(int[] nums) {
+        int l = 0,r = nums.length - 1;
+        if (nums.length <= 2) {
+            return nums[0];
+        }
+        if (nums[1] != nums[0]) {
+            return nums[0];
+        }
+        if (nums[nums.length - 1] != nums[nums.length - 2]) {
+            return nums[nums.length - 1];
+        }
+        while (l <= r) {
+            int m = l + (r - l)/2;
+            if (nums[m + 1] != nums[m] && nums[m] != nums[m - 1]) {
+                return nums[m];
+            }
+            if (m - 1 >= 0 && nums[m] == nums[m - 1]) {
+                r = m - 1;
+            }else if (m + 1 < nums.length && nums[m] == nums[m + 1]) {
+                l = m + 1;
+            }else {
+                return nums[m];
+            }
+        }
+        return nums[l];
+    }
 }

src/DFS/图的连通分量个数.java

@@ -29,5 +29,6 @@ public void dfs (int [][]M, int j, int []visit) {
         }
     }
 
+
 }
 

src/DFS/岛屿的最大面积.java

@@ -0,0 +1,41 @@
+package DFS;
+
+/**
+ * Created by 周杰伦 on 2018/7/18.
+ */
+public class 岛屿的最大面积 {
+    public static void main(String[] args) {
+        int [][]a = {{1,1,0,0,0},{1,1,0,0,0},{0,0,0,1,1},{0,0,0,1,1}};
+        System.out.println(maxAreaOfIsland(a));
+    }
+    public static int maxAreaOfIsland(int[][] grid) {
+        int [][]visit = new int[grid.length][grid[0].length];
+        int max = 0;
+        for (int i = 0;i < grid.length;i ++) {
+            for (int j = 0;j < grid[0].length;j ++) {
+                if (grid[i][j] == 1) {
+                    max = Math.max(max, dfs(grid, i, j, visit, 0));
+                }
+            }
+        }
+        return max;
+    }
+
+    public static int dfs(int [][]grid, int x, int y, int [][]visit, int count) {
+        if (x < 0 || x > grid.length - 1 || y < 0 || y > grid[0].length - 1) {
+            return count;
+        }
+        if (visit[x][y] == 1 || grid[x][y] == 0) {
+            return count;
+        }
+
+        visit[x][y] = 1;
+        count ++;
+
+        count += dfs(grid, x + 1, y, visit, 0);
+        count += dfs(grid, x - 1, y, visit, 0);
+        count += dfs(grid, x, y + 1, visit, 0);
+        count += dfs(grid, x, y - 1, visit, 0);
+        return count;
+    }
+}

src/DFS/查找最大的连通面积.java

@@ -1,6 +1,7 @@
 package DFS;
 
 import java.util.Arrays;
+import java.util.Stack;
 
 /**
  * Created by 周杰伦 on 2018/3/30.
@@ -45,4 +46,34 @@ public static void dfs(int [][]grid,int [][]visit, int x, int y) {
         dfs(grid,visit,x ,y - 1);
         return;
     }
+
+    //非递归写法
+//    class Pos{
+//        int x;
+//        int y;
+//        int count;
+//
+//        public Pos(int x, int y, int count) {
+//            this.x = x;
+//            this.y = y;
+//            this.count = count;
+//        }
+//    }
+//    public int stack(int [][]grid,int [][]visit, int x, int y) {
+//        Stack<Pos> stack = new Stack<>();
+//        stack.push(new Pos(x, y, 0));
+//        int [][]pos = {{0,1}, {0, -1}, {1, 0}, {-1, 0}};
+//        while (!stack.isEmpty()) {
+//            Pos init = stack.peek();
+//            for (int i = 0; i < pos.length; i++) {
+//                int x0 = x + pos[i][0];
+//                int y0 = y + pos[i][1];
+//                if (visit[x0][y0] == 0 && grid[x0][y0] == 1) {
+//                    stack.push(new Pos(x0, y0, init.count + 1));
+//                    break;
+//                }
+//            }
+//            stack.pop();
+//        }
+//    }
 }