mock myself

fourSum.cpp

#include <bits/stdc++.h>
using namespace std;

#define vi vector<int>

class Solution {
	public:
		vector<vi> fourSum(vi &v, int n) {
			sort(v.begin(),v.end());
			set<vi> s;
			int sz, r, lo, hi, i, j;
			
			sz = v.size();
			for (i = 0; i <= sz - 4; i++) {
				for (j = i + 1; j <= sz - 3; j++) {
					r = n - (v[i] +v[j]);

					lo = j + 1, hi = sz - 1;

					while (lo < hi) {
						if (r == v[lo]+v[hi]) {
							vector<int> tmp = { v[i], v[j], v[lo], v[hi]};
							s.insert(tmp);
							lo++, hi--;
						} else if (v[lo]+v[hi] < r) {
							lo++;
						} else if (v[lo]+v[hi] > r) {
							hi--;
						}
					}
				}
			}
			vector<vi> result(s.begin(), s.end());
			return result;			
		}
};

int main() {
	vi test = {2, 7, 4, 0, 9, 5, 1, 3};
	int n = 20;
	Solution s;
	vector<vi> afs = s.fourSum(test, n);
	for(auto &v: afs) {
		for(auto &e: v) {
			cout << e << " ";
		}
		cout << endl;
	}
	return 0;
}

meetingPlanner.cpp

#include <bits/stdc++.h>
using namespace std;
#define vi vector<int>

const int N = 2;
class Solution {
  public:
    vi meetingPlanner(vector<vi> &slotsA, vector<vi> &slotsB, int n) {
      // your code goes here
      vi ret;
      int i, j;
      i = j = 0;
      //O(M+N)

      while(i < slotsA.size() && j < slotsB.size()){
         int st = max(slotsA[i][0],slotsB[j][0]);
         int fin = min(slotsA[i][1],slotsB[j][1]);
         
         if(st + n <= fin) {
             ret.push_back(st);
             ret.push_back(st+n);
             return ret;
         } else if (slotsA[i][0] < slotsB[j][0]){
           i++;
         } else {
           j++;
         }
      }
      return ret;
    }
};

int main() {
  vector<vi> a = {{10, 50}, {60, 120},{140, 210}};
  vector<vi> b = {{0,15},{60,70}};
  int dur = 8;
  Solution afs;
  vector<int> ans = afs.meetingPlanner(a, b, dur);
  if(ans.size() == 0) puts("null");
  else {
    for(int i = 0; i < ans.size(); i++)
      cout << ans[i] << " ";
    cout << endl;
  }
  return 0;
}