LeetCode 3Sum Closest

最新推荐文章于 2020-01-16 15:31:01 发布

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本文介绍了一个算法问题，即在给定的整数数组中找到三个整数，使得它们的和尽可能接近指定的目标值。通过排序数组并使用双指针技巧，实现高效求解。

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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).

题意：求集合中三个数和最接近目标数字的结果

思路：和上面那道题目LeetCode 3Sum差不多，少了去重

class Solution {
public:
    int threeSumClosest(vector<int> &num, int target) {
        sort(num.begin(), num.end());

        int ans;
        int flag = 1;

        for (int i = 0; i < num.size(); i++) {
            int s = i + 1;
            int e = num.size() - 1;

            while (s < e) {
                int sum = num[i] + num[s] + num[e];
                if (flag) {
                    ans = sum;
                    flag = 0; 
                } else if (abs(sum-target) < abs(ans-target))
                    ans = sum;

                if (sum == target) return sum; 
                if (sum > target)
                    e--;
                else if (sum < target)
                    s++;
            }
        }

        return ans;
    }
};