https://practice.geeksforgeeks.org/problems/triplet-sum-in-array/0

``````class Solution {
public:
bool find3Numbers(int A[], int n, int X) {
sort(A, A + n);
for (int i = 0; i < n - 2; i++) {
int l = i + 1, r = n - 1;

while (l < r) {
int sum = A[i] + A[l] + A[r];
if (sum == X)
return true;
else if (sum < X) {
l++;
} else {
r--;
}
}
}
return false;
}
};
``````

## When `X = 0`

https://leetcode.com/problems/3sum/ 2 pointer, avoid duplicates since `vector<vector<int>>` returned

``````class Solution {
public:
vector<vector<int>> threeSum(vector<int> &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]) {
int l = i + 1, r = n - 1;

while (l < r) {
if (nums[l] + nums[r] + nums[i] == 0) {
vector<int> triplet = {nums[l], nums[r], nums[i]};
ans.push_back(triplet);

while (l < r && nums[l] == nums[l + 1]) {
l++;
}
while (l < r && nums[r] == nums[r - 1]) {
r--;
}

l++;
r--;
} else if (nums[l] + nums[r] + nums[i] > 0) {
r--;
} else {
l++;
}
}
}
}
return ans;
}
};
``````