16 3Sum Closest

public class Solution {
    public int threeSumClosest(int[] nums, int target) {
        if (nums == null || nums.length < 3) {
            return Integer.MAX_VALUE;
        }
        Arrays.sort(nums);
        int min = Integer.MAX_VALUE/2;//otherwise it will overflow for (min - target);

        for (int i = 0; i < nums.length; i++) {
            int left = i + 1;
            int right = nums.length-1;
            while (left < right) {
                int sum = nums[i] + nums[left] + nums[right];
                if (sum == target) {
                    return target;
                } else if (sum < target) {
                    left++;
                } else {
                    right--;
                }
                min = Math.abs(sum - target) < Math.abs(min - target) ? sum : min;
            }
        }
        return min;
    }
}

注意红字部分！，min 开始应该赋值为Integer.MAX_VALUE/2 否则后面的表达式（min - target）如果target为负数会溢出overflow