[Leetcode] 3Sum Closest

原创于 2012-12-01 13:56:04 发布 · 601 阅读

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本文介绍了一个解决三数之和最接近目标值问题的C++算法实现。通过先对输入数组进行排序，然后使用双指针技巧遍历数组来寻找与目标值最接近的三个数之和。该算法能有效找到最佳组合并返回其和。

class Solution {
public:
    int threeSumClosest(vector<int> &num, int target) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sort(num.begin(), num.end());
        int res = 0;
        int diff = INT_MAX;
        
        for (int i = 0; i < num.size(); ++i)
        {
            int j = i + 1;
            int k = num.size() - 1;
            
            int tempSum = 0;
            while (j < k)
            {
                tempSum = num[i] + num[j] + num[k];
                if (tempSum == target)
                    return target;
                else if (tempSum > target)
                {
                    if (diff > tempSum - target)
                    {
                        diff = tempSum - target;
                        res = tempSum;
                        
                    }
                    k--;
                }
                else if (tempSum < target)
                {
                    if (diff > target - tempSum)
                    {
                        diff = target - tempSum;
                        res = tempSum;
                        
                    }
                    j++;
                }
            }
        }
        
        return res;
    }
};