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find_duplicates.cpp
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find_duplicates.cpp
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#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
// Postioning Method
int duplicate_03(vector<int>& arr){
while(arr[0] != arr[arr[0]])
swap(arr[0],arr[arr[0]]);
return arr[0];
}
// Negative marking method
int duplicate_02(vector<int>& arr){
for(int i = 0; i < arr.size(); i++){
int ele = abs(arr[i]);
if(arr[ele] < 0)
return ele;
arr[ele] *= -1;
}
return -1;
}
// sort and return
int duplicate_01(vector<int>& arr){
sort(arr.begin(),arr.end());
for(int i = 0; i < arr.size()-1; i++){
if(arr[i] == arr[i+1])
return arr[i];
}
return -1;
}
int duplicate(vector<int>& arr){
for(int i = 0; i < arr.size(); i++){
for(int j = i+1; j < arr.size(); j++){
if(arr[i] == arr[j])
return arr[i];
}
}
return -1;
}
int main()
{
vector<int> arr{1,2,3,4,5,6,7,8,9,6};
cout<<"Duplicate ele: "<<duplicate_03(arr);
return 0;
}