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twosumset.cpp
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twosumset.cpp
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#include <bits/stdc++.h>
using namespace std;
int binarySearch(int arr[],int number,int start,int end){
while(start<=end){
int mid=(end+start)/2;
if(arr[mid]==number){
return mid;
}
if(arr[mid]<number){
start = mid+1;
}
else{
end = mid-1;
}
}
return -1;
}
vector<vector<int>> twosum(int arr[],int size,int sum){
vector<vector<int>> twonumber;
// method-1
//O(nlogn) - using sorting and searching
// sort(arr,arr+size);
// for(int i=0;i<size;i++){
// int index = binarySearch(arr,sum-arr[i],i,size-1);
// if(index!=-1 && index!=i){
// vector<int> temp;
// temp.push_back(arr[i]);
// temp.push_back(arr[index]);
// twonumber.push_back(temp);
// }
// }
// method-2
sort(arr,arr+size);
int l=0;
int r= size-1;
while(l<r){
int csum = arr[l]+arr[r];
if(csum==sum){
vector<int> temp;
temp.push_back(arr[l]);
temp.push_back(arr[r]);
twonumber.push_back(temp);
l++;
r--;
}
else if(csum<sum){
l++;
}
else{
r--;
}
}
return twonumber;
}
//find subsets which as sum of 6
int sumset(int arr[],int index,vector<int> subset,int sum){
if(sum<0 || index>4){
return 0;
}
if(sum==0){
for(auto e:subset){
cout<<e<<" ";
}cout<<endl;
return 1;
}
subset.push_back(arr[index]);
sumset(arr,index+1,subset,sum-arr[index]);
subset.pop_back();
sumset(arr,index+1,subset,sum);
return 0;
}
int main() {
int arr[]={1,2,3,3,4,5};
vector<vector<int>> twonumber = twosum(arr,6,6);
for(auto numbers: twonumber){
for(auto number:numbers){
cout<<number<<" ";
}cout<<endl;
}
return 0;
}