vector<vector<int>> threeSum(vector<int>& nums)，用中文描述一下这句代码的意思C++

nums) {
vector<vector<int>> ans;
sort(nums.begin(), nums.end());
int n = nums.size();
for (int i = 0; i < n - 2; i++) {
if (i > 0 && nums[i] == nums[i - 1]) continue;
int l = i + 1, r = n - 1;
while (l < r) {
int sum = nums[i] + nums[l] + nums[r];
if (sum == 0) {
ans.push_back({nums[i], nums[l], nums[r]});
l++;
r--;
while (l < r && nums[l] == nums[l - 1]) l++;
while (l < r && nums[r] == nums[r + 1]) r--;
} else if (sum < 0) {
l++;
} else {
r--;
}
}
}
return ans;
}