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Rearrange Array InterviewBit Solution
Updated: Sep 8, 2020
Problem: Rearrange Array
Problem Description:
Rearrange a given array so that Arr[i] becomes Arr[Arr[i]] with O(1) extra space.
Example:
Input : [1, 0]
Return : [0, 1] Lets say N = size of the array. Then, following holds true :
All elements in the array are in the range [0, N-1]
N * N does not overflow for a signed integer
Solution:
void Solution::arrange(vector<int> &A) {
int n=A.size();
for(int i=0;i<A.size();i++){
A[i]=A[i]*n;
}
for(int i=0;i<A.size();i++){
A[i]=A[i]+A[A[i]/n]/n;
}
for(int i=0;i<A.size();i++){
A[i]= A[i]%n;
}
}
The part where the old and new values are packed into the same integer is what made this click for me—I’d never thought of using the modulo step to peel them apart. It’s a bit like how I track my casino payments at https://kasinomaksut.com: the original balance and the pending transaction sit in one place until the final amount is settled.