leetcode/src/s0016_3sum_closest.cpp

#include "s0016_3sum_closest.hpp"

// 和上一道一样，排序 + 双指针

int S0016::threeSumClosest(vector<int>& nums, int target) {
  int sum = nums[0] + nums[1] + nums[2];
  int len = nums.size();
  sort(nums.begin(), nums.end());
  for (int i{1}; i < len - 1; i++) {
    for (int j{0}, k = len - 1; j != k && i != j && i != k;) {
      if (nums[i] + nums[j] + nums[k] > target) {
        if (abs(nums[i] + nums[j] + nums[k] - target) < abs(sum - target)) {
          sum = nums[i] + nums[j] + nums[k];
        }
        k--;
      } else if (nums[i] + nums[j] + nums[k] < target) {
        if (abs(nums[i] + nums[j] + nums[k] - target) < abs(sum - target)) {
          sum = nums[i] + nums[j] + nums[k];
        }
        j++;
      } else {
        return nums[i] + nums[j] + nums[k];
      }
    }
  }
  return sum;
}