259.较小的三数之和

方法：排序+双指针

class Solution {public int threeSumSmaller(int[] nums, int target) {Arrays.sort(nums);int k = 0;for(int i = 0;i<nums.length;i++){int start = i + 1,end = nums.length - 1;while(start < end){int sum = nums[start] + nums[end] + nums[i];if(sum < target){k += (end - start);  //因为数组排好序了，所以start到end中的数都小于targetstart++;}if(sum >= target){end--;}}}return k;}
}