leetcode

Random Problem

2 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/ Problems/0018.cpp b/ Problems/0018.cpp

@@ -0,0 +1,30 @@

class Solution {

public:

vector<vector<int>> fourSum(vector<int> &nums, int target) {

vector<vector<int>> res;

int n = nums.size();

sort(nums.begin(), nums.end());

for (int i = 0; i < n; i++) {

for (int j = i + 1; j < n; j++) {

long long goal = (long long)target - nums[i] - nums[j];

int k = j + 1, l = n - 1;

while (k < l) {

long long crnt = nums[k] + nums[l];

if (crnt > goal)

l--;

else if (crnt < goal)

k++;

else {

res.push_back({nums[i], nums[j], nums[k], nums[l]});

k++, l--;

while (k < l && nums[l] == nums[l + 1]) l--;

}

}

while (j + 1 < n && nums[j] == nums[j + 1]) ++j;

}

while (i + 1 < n && nums[i] == nums[i + 1]) ++i;

}

return res;

}

};

diff --git a/ README.md b/ README.md

@@ -40,6 +40,7 @@ for solving problems. | 0015 | Medium | [3Sum](Problems/0015.cpp) | | 0016 | Medium | [3Sum Closest](Problems/0016.cpp) | | 0017 | Medium | [Letter Combinations of a Phone Number](Problems/0017.cpp) |

| 0018 | Medium | [4Sum](Problems/0018.cpp) |

| 0019 | Medium | [Remove Nth Node From the End of List](Problems/0019.cpp) | | 0020 | Easy | [Valid Parentheses](Problems/0020.cpp) | | 0021 | Easy | [Merge Two Sorted Lists](Problems/0021.cpp) |