LeetCode题解——3Sum Closest

最新推荐文章于 2020-12-22 11:12:17 发布

原创最新推荐文章于 2020-12-22 11:12:17 发布 · 535 阅读

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本文介绍了解决问题的方法，即在给定数组中找到三个整数，使得它们的和最接近指定的目标数。通过排序数组并使用双指针技巧，可以有效地解决此问题。

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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).

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

只要理解了前一道3sum的题，这道题就迎刃而解