leetcode-15 三数之和

/**
 * @param {number[]} nums
 * @return {number[][]}
 */
var threeSum = function (nums) {
  // 排序
  // 固定头 + 双指针
  const result = [];
  nums.sort((a, b) => a - b);
  const len = nums.length;
  for (let i = 0; i < len - 2; i++) {
    // 去重
    if (i > 0 && nums[i] === nums[i - 1]) continue;
    let left = i + 1,
      right = len - 1;
    while (left < right) {
      const sum = nums[i] + nums[left] + nums[right];
      if (sum === 0) {
        result.push([nums[i], nums[left], nums[right]]);
        while (left < right && nums[left] === nums[left + 1]) left++;
        while (left < right && nums[right] === nums[right - 1]) right++;
        // 找到最后一个和它相等的数
        left++;
        right--;
      } else if (sum < 0) {
        left++;
      } else {
        right--;
      }
    }
  }
  return result;
};
console.log(threeSum([-1,0,1,2,-1,-4]));
console.log(
  threeSum([2, -3, 0, -2, -5, -5, -4, 1, 2, -2, 2, 0, 2, -4, 5, 5, -10])
);