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  • 3Sum Closest

    【题目】

    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).

    【分析】

    1.思路与3 Sum类似,采用两层循环的方式。

    2.需要记录当前3个值的和与target的差的最小值

    【算法实现】

    public class Solution {
        public int threeSumClosest(int[] num, int target) {
            Arrays.sort(num);
            if(num.length<3)
                return 0;
            int res=num[0]+num[1]+num[2];
            for(int i=0;i<num.length;i++) {
                int start=i+1;
                int end=num.length-1;
                while(start<end) {
                    int sum=num[i]+num[start]+num[end];
                    if(Math.abs(sum-target)<Math.abs(res-target))
                        res=sum;
                    else if(sum==target)
                        return sum;
                    else if(sum>target)
                        end--;
                    else 
                        start++;
                }
            }
            return res;
        }
    }
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  • 原文地址:https://www.cnblogs.com/hwu2014/p/4460882.html
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