LeetCode : 3Sum Closest [java]

最新推荐文章于 2021-02-21 13:37:33 发布

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#LeetCode #3Sum Closest

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本文介绍了一个算法问题的解决方案，即在给定整数数组中找到三个数，使得这三个数的和最接近给定的目标值。通过排序和双指针技巧实现了高效的求解方法。

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.

    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).

思路：同上篇博客，稍加变化而已。

import java.util.Arrays;

public class Solution {
    public int threeSumClosest(int[] nums, int target) {
		if (nums.length < 3) {
			return 0;
		}
		Arrays.sort(nums);
		int value = nums[0] + nums[1] + nums[2];
		for (int i = 0; i < nums.length; i++) {
			if (i >= 1 && nums[i] == nums[i - 1]) {
				continue;
			}
			int j = i + 1;
			int k = nums.length - 1;
			while (j < k) {
				int nowValue = nums[i] + nums[j] + nums[k];
				if (Math.abs(nowValue - target) < Math.abs(value - target)) {
					value = nowValue;
				}
				if (nowValue > target) {
					while (k > j && k <= nums.length - 2 && nums[k] == nums[k - 1]) {
						k--;
					}
					k--;
				} else if (nowValue < target) {
					while (j < k && j >= 1 && nums[j] == nums[j + 1]) {
						j++;
					}
					j++;
				} else {
					return target;
				}
			}
		}
		return value;
    }
}