16. 3Sum Closest

Author: zhangbo54

src/leetcode/_16_/Main.java

@@ -0,0 +1,61 @@
+package leetcode._16_;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Created by zhangbo54 on 2019-03-04.
+ */
+public class Main {
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        System.out.println(solution.threeSumClosest(new int[]{4,0,5,-5,3,3,0,-4,-5}, -2));
+
+        // Integer.parseInt("1" + Integer.MAX_VALUE);
+        //  -4 -1, -1, 0, 1, 2,
+    }
+}
+
+class Solution {
+    public int threeSumClosest(int[] nums, int target) {
+        int sum = 0;
+        if (nums.length < 3) {
+            return sum;
+        }
+        Arrays.sort(nums);
+        int minGap = nums[0] + nums[1] + nums[2] - target;
+        for (int i = 0; i < nums.length - 1; i++) {
+            if (nums[i] > 0 && nums[i] > target) {
+                continue;
+            }
+            if (i > 1 && nums[i] == nums[i - 1]) {
+                continue;
+            }
+            int numSum = target - nums[i];
+            int x = i + 1;
+            int y = nums.length - 1;
+            while (x < y ) {
+                int tempSum = nums[x] + nums[y];
+                if (tempSum == numSum) {
+                    return target;
+                } else {
+                    if (Math.abs(minGap) > Math.abs(tempSum - numSum)) {
+                        minGap = tempSum - numSum;
+                    }
+                    if (tempSum > numSum) {
+                        y--;
+                    } else {
+                        x++;
+                    }
+                }
+            }
+        }
+        return minGap + target;
+    }
+}

src/leetcode/_16_/solution.md

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+### [16\. 3Sum Closest](https://leetcode.com/problems/3sum-closest/)
+
+Difficulty: **Medium**
+
+
+Given an array `nums` of _n_ integers and an integer `target`, find three integers in `nums` such that the sum is closest to `target`. Return the sum of the three integers. You may assume that each input would have exactly one solution.
+
+**Example:**
+
+```
+Given array nums = [-1, 2, 1, -4], and target = 1.
+
+The sum that is closest to the target is 2\. (-1 + 2 + 1 = 2).
+```
+
+
+#### Solution
+
+Language: **Java**
+
+```java
+class Solution {
+    public int threeSumClosest(int[] nums, int target) {
+        int sum = 0;
+        if (nums.length < 3) {
+            return sum;
+        }
+        Arrays.sort(nums);
+        int minGap = nums[0] + nums[1] + nums[2] - target;
+        for (int i = 0; i < nums.length - 1; i++) {
+            if (nums[i] > 0 && nums[i] > target) {
+                continue;
+            }
+            if (i > 1 && nums[i] == nums[i - 1]) {
+                continue;
+            }
+            int numSum = target - nums[i];
+            int x = i + 1;
+            int y = nums.length - 1;
+            while (x < y ) {
+                int tempSum = nums[x] + nums[y];
+                if (tempSum == numSum) {
+                    return target;
+                } else {
+                    if (Math.abs(minGap) > Math.abs(tempSum - numSum)) {
+                        minGap = tempSum - numSum;
+                    }
+                    if (tempSum > numSum) {
+                        y--;
+                    } else {
+                        x++;
+                    }
+                }
+            }
+        }
+        return minGap + target;
+    }
+}
+                    if (Math.abs(gap) > Math.abs(tempSum - numSum)) {
+```