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LeetCode 16.3Sum Cloest

发表于 更新于 分类于 Disqus：
求与目标值最近的三个数的和，返回它们之间的差。

16.3Sum Cloest

Description:

Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.

example

For example, given array S = {-1 2 1 -4}, and target = 1.

The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).

题目理解：输入一个数组和一个目标值，求数组中三个数的和，返回和与目标值之间的最小差值。

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public class Solution {
    public int threeSumClosest(int[] nums, int target) {
        int dis = Integer.MAX_VALUE, result = -1, m = nums.length;
        Arrays.sort(nums);
        for ( int i = 0, bound = m - 2 ; i < bound && dis != 0 && nums[i] - target < dis; ) {
            int l = i + 1, r = m - 1;
            while ( l < r ) {
                int sum = nums[i] + nums[l] + nums[r];
                int temp_dis = sum - target;
                temp_dis = temp_dis > 0 ? temp_dis : -temp_dis;
                if ( temp_dis < dis ) {
                    dis = temp_dis;
                    result = sum;
                }
                if ( sum - target < 0 ) l++;
                else r--;
            }
            i++;
            while ( i < bound && nums[i] == nums[i-1] ) i++;
        }
        return result;
    }
}

方法和3Sum几乎一样，只是多进行一下距离的比较。

复杂度 n^2, 运行时间 18ms.

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