16.3Sum Closest

最新推荐文章于 2020-03-05 16:51:32 发布

转载最新推荐文章于 2020-03-05 16:51:32 发布 · 55 阅读

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原文链接：http://www.cnblogs.com/smallredness/p/10672833.html

本文提供了一种解决三数之和最接近目标值问题的有效算法。通过先排序再使用双指针技术，该算法能在O(n^2)的时间复杂度内找到数组中三个整数相加最接近给定目标值的组合。

class Solution {
public:
    int threeSumClosest(vector<int>& nums, int target) {
        int closest = nums[0] + nums[1] + nums[2];
        int diff = abs(closest - target);
        sort(nums.begin(), nums.end());
        for (int i = 0; i < nums.size() - 2; ++i) {
            int left = i + 1, right = nums.size() - 1;
            while (left < right) {
                int sum = nums[i] + nums[left] + nums[right];
                int newDiff = abs(sum - target);
                if (diff > newDiff) {
                    diff = newDiff;
                    closest = sum;
                }
                if (sum < target) ++left;
                else --right;
            }
        }
        return closest;
    }
};

转载于:https://www.cnblogs.com/smallredness/p/10672833.html