20190310

Author: mJackie

code/lc16.java

@@ -0,0 +1,29 @@
+package code;
+
+import java.util.Arrays;
+/*
+ * 16. 3Sum Closest
+ * 题意：找出3个数的和最接近target
+ * 难度：Medium
+ * 分类：Array, Two Pointers
+ * 思路：3sum的思路，每次记下最接近的res即可
+ * Tips：
+ */
+public class lc16 {
+    public int threeSumClosest(int[] nums, int target) {
+        int res = nums[0]+nums[1]+nums[2];
+        Arrays.sort(nums);
+        for (int i = 0; i < nums.length-2 ; i++) {
+            int start = i+1;
+            int end = nums.length-1;
+            while(start<end){
+                int sum = nums[i] + nums[start] + nums[end];
+                if(sum==target) return target;
+                else if(sum<target) start++;
+                else if(sum>target) end--;
+                if(Math.abs(sum-target)<Math.abs(res-target)) res = sum;
+            }
+        }
+        return res;
+    }
+}

code/lc9.java

@@ -0,0 +1,20 @@
+package code;
+/*
+ * 9. Palindrome Number
+ * 题意：判断数字是否是回文数字
+ * 难度：Easy
+ * 分类：Math
+ * 思路：不转换字符串的思路就是把数字反转了以后，比较是否相等
+ * Tips：
+ */
+public class lc9 {
+    public boolean isPalindrome(int x) {
+        int rev = 0;
+        int temp = x;
+        while(x>0){
+            rev = rev*10 + x%10;
+            x = x/10;
+        }
+        return rev == temp;
+    }
+}

readme.md

@@ -32,11 +32,13 @@ LeetCode 指南
 | 005 [Java](./code/lc5.java)
 | 007 [Java](./code/lc7.java)
 | 008 [Java](./code/lc8.java)
+| 009 [Java](./code/lc9.java)
 | 010 [Java](./code/lc10.java)
 | 011 [Java](./code/lc11.java)
 | 013 [Java](./code/lc13java)
 | 014 [Java](./code/lc14java)
 | 015 [Java](./code/lc15java)
+| 016 [Java](./code/lc16java)
 | 017 [Java](./code/lc17.java)
 | 019 [Java](./code/lc19.java)
 | 020 [Java](./code/lc20.java)