Month: January 2025

int countTriangles(vector<int>& arr) {
        // code here
        int count = 0;
        sort(arr.begin(), arr.end());
        for(int i=2; i<arr.size(); i++) {
            int j=0, k=i-1;
            while(j<k) {
                if(arr[j]+arr[k] > arr[i]) {
                    count += k-j;
                    k--;
                } else {
                    j++;
                }
            }
        }
        return count;
    }

int countPairs(vector<int> &arr, int target) {
        // Complete the function
        int count = 0, i=0, j=arr.size()-1;
        while(i<j) {
            int sum = arr[i] + arr[j];
            if(sum < target) i++;
            else if(sum > target) j--;
            else {
                int el1 = arr[i], el2=arr[j];
                int ci = 0, cj=0;
                
                while(arr[i] == el1 && i<=j) ci++, i++;
                while(arr[j] == el2 && i<=j) cj++, j--;
                
                if(el1 == el2) count += ci*(ci-1)/2;
                else count += ci*cj; 
            }
        }
        return count;
    }

int countPairs(vector<int> &arr, int target) {
        // Your code here
        sort(arr.begin(), arr.end());
        int count=0, l=0, r=arr.size()-1;
        while(l<r) {
            int sum = arr[l]+arr[r];
            if(sum < target) {
                count += r-l;
                l++;
            } else {
                r--;
            }
        }
        return count;
    }

int countTriplets(vector<int> &arr, int target) {
        // Code Here
        int count = 0;
        int n = arr.size();
        for(int i=0; i<n-2; i++) {
            int j = i+1, k=n-1;
            while(j<k) {
                int sum = arr[i] + arr[j] + arr[k];
                if(sum < target) j++;
                else if(sum > target) k--;
                else if(sum == target) {
                count++;
                int temp = j+1;
                while(arr[temp] == arr[temp-1] && temp<k) {
                    count++;
                    temp++;
                    }
                    k--;
                } 
            }
            
        }
        return count;
    }

long subarrayXor(vector<int> &arr, int k) {
        // code here
        int ans = 0, prefixXor = 0;
        unordered_map<int, int> mp;
        
        for(int i=0; i<arr.size(); i++) {
            prefixXor ^= arr[i];
            if(mp.find(prefixXor^k) != mp.end())
                ans += mp[prefixXor^k];
            if(prefixXor == k)
                ans++;
            mp[prefixXor]++;
        }
        return ans;
    }

int countSubarrays(vector<int> &arr, int k) {
        // code here
        unordered_map<int, int> map;
        int count = 0, sum = 0;
        
        for(int i=0; i<arr.size(); i++) {
            sum+= arr[i];
            if(sum==k) count++;
            if(map.find(sum-k) != map.end()) count+=map[sum-k];
            map[sum]++;
        }
        return count;
    }

vector<vector<string>> anagrams(vector<string>& arr) {
        // code here
        vector<vector<string>> ret;
        unordered_map<string, vector<string>> anagrams;
        
        for(int i=0; i<arr.size(); i++) {
            string key = arr[i];
            sort(key.begin(), key.end());
            anagrams[key].push_back(arr[i]);
        }
        
        for(auto x:anagrams) {
            ret.push_back(x.second);
        }
        return ret;
    }