[Leetcode][016] 3Sum Closest (Java)

题目: https://leetcode.com/problems/3sum-closest/

【标签】Array; Two Pointers

【个人分析】

　　这道题和它的姊妹题 3Sum 非常类似， 就不再多说了，具体一些的分析可以参考 [Leetcode][015] 3Sum

 

public class Solution {
    public int threeSumClosest(int[] nums, int target) {
        int result = target;
        int len = nums.length;
        if (len < 3) {
            return 0;
        }
        Arrays.sort(nums);
        for (int i = 0; i < len; i++) {
            int number = nums[i];
            
            int leftIndex = i + 1;
            int rightIndex = len - 1;
            while (leftIndex < rightIndex) {
                int threeSum = number + nums[leftIndex] + nums[rightIndex];
                if (threeSum == target) {
                    // best result found!
                    return target;
                } else {
                    // update global result
                    if ( result == target || 
                            Math.abs(target - threeSum) < Math.abs(target - result)) {
                        result = threeSum;
                    }
                    if (threeSum < target) {
                        while (leftIndex < rightIndex && 
                                nums[leftIndex] == nums[leftIndex + 1]) {
                            leftIndex++;
                        }
                        leftIndex++;
                    } else {
                        while (leftIndex < rightIndex && 
                                nums[rightIndex] == nums[rightIndex - 1]) {
                            rightIndex--;
                        }
                        rightIndex--;
                    }
                }
            }
        }
        return result;
    }

}