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DSA_9.cpp
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DSA_9.cpp
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/**
* Author - Sandeep Das
1.) Q4 of 450DSA
2.) Problem - Sort an array of 0's,1's and 2's without using any sorting algo
3.) Input : arr[]= {0 2 1 2 0}
Output : arr[]= {0 0 1 2 2}
4.) T.C. = O(n)
5.) Algo :- Take 23 ptrs. low,mid,high. Initialize them as low=0,mid=0 and high=n-1
Base case - low<mid<high || 0<mid<2
while(mid<=high) =>
if(ele[mid] = 0) -> swap(ele[low],ele[mid]), low++, mid++
else-if(ele[mid] = 1) -> mid++
else -> swap(ele[mid],ele[high]), high--
*/
#include <iostream>
#include <algorithm>
using namespace std;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int n;
cin>>n;
int nums[n];
for(int i=0;i<n;i++){
cin>>nums[i];
}
int low=0,mid=0,high=n-1;
while(mid<=high){
switch(nums[mid]){
case 0:
swap(nums[low++],nums[mid++]);
break;
case 1:
mid++;
break;
case 2:
swap(nums[mid],nums[high--]);
break;
}
}
for(int i=0;i<n;i++){
cout<<nums[i]<<" ";
}
return 0;
}