add

5.leetcode/src/com/fanxb/common/Q1449.java

@@ -0,0 +1,41 @@
+package com.fanxb.common;
+
+import java.util.Arrays;
+
+/**
+ * Created with IntelliJ IDEA
+ * x 的平方根
+ * 地址： https://leetcode-cn.com/problems/sqrtx/
+ * 思路： 双路规避排序查找
+ *
+ *
+ * @author fanxb
+ * Date: 2020/6/11 9:56
+ */
+public class Q1449 {
+    public String largestNumber(int[] cost, int target) {
+        int[] f = new int[target + 1];
+        Arrays.fill(f, Integer.MIN_VALUE);
+        f[0] = 0;
+        for (int i = 1; i <= 9; i++) {
+            int u = cost[i - 1];
+            for (int j = u; j <= target; j++) {
+                f[j] = Math.max(f[j], f[j - u] + 1);
+            }
+        }
+        if (f[target] < 0) return "0";
+        StringBuilder ans = new StringBuilder();
+        for (int i = 9, j = target; i >= 1; i--) {
+            int u = cost[i - 1];
+            while (j >= u && f[j] == f[j - u] + 1) {
+                ans.append(i);
+                j -= u;
+            }
+        }
+        return ans.toString();
+    }
+
+    public static void main(String[] args) {
+        System.out.println(new Q1449().largestNumber(new int[]{4,3,2,5,6,7,2,5,5},9));
+    }
+}

5.leetcode/src/com/fanxb/common/Q278.java

@@ -0,0 +1,30 @@
+package com.fanxb.common;
+
+/**
+ * Created with IntelliJ IDEA
+ *
+ * @author fanxb
+ * Date: 2020/6/11 9:56
+ */
+public class Q278 {
+    private boolean isBadVersion(int n){
+        return true;
+    }
+
+    public int firstBadVersion(int n) {
+        int left=1,right=n;
+        while (left<right){
+            int mid =(int) ((long)left+right>>1);
+            if(isBadVersion(mid)){
+                right=mid;
+            }else{
+                left=mid+1;
+            }
+        }
+        return left;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(new Q278().firstBadVersion(16));
+    }
+}

5.leetcode/src/com/fanxb/common/Q374.java

@@ -0,0 +1,31 @@
+package com.fanxb.common;
+
+/**
+ * 两数相加
+ *
+ * @author fanxb
+ * @date 2021/6/1
+ **/
+public class Q374 {
+    private static int target=6;
+    private static int guess(int num){
+        return Integer.compare(target, num);
+    }
+
+    public int guessNumber(int n) {
+        int l=1,r=n;
+        while (l<r){
+            int mid = l+(r-l)/2;
+            if(guess(mid)==1){
+                l=mid+1;
+            }else{
+                r=mid;
+            }
+        }
+        return l;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(new Q374().guessNumber(10));
+    }
+}

5.leetcode/src/com/fanxb/common/Q852.java

@@ -0,0 +1,35 @@
+package com.fanxb.common;
+
+/**
+ * 两数相加
+ *
+ * @author fanxb
+ * @date 2021/6/1
+ **/
+public class Q852 {
+    public int peakIndexInMountainArray(int[] arr) {
+        int l=0,r=arr.length-1;
+        while (l<r){
+            int mid = l+(r-l)/2;
+            if(arr[mid]==arr[mid+1]){
+                //无法判断mid处于什么位置
+                if(arr[l]<=arr[mid]){
+                    l++;
+                }else{
+                    r--;
+                }
+            }else if(arr[mid]>arr[mid+1]){
+                //说明是递减的
+                r=mid;
+            }else{
+                //说明是递增的
+                l=mid+1;
+            }
+        }
+        return l;
+    }
+
+    public static void main(String[] args) {
+        System.out.println(new Q852().peakIndexInMountainArray(new int[]{0,10,5,2}));
+    }
+}