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Integer Replacement in C++
Suppose we have a positive integer n and we can do these operations as follow −
If n is even, replace n with n/2.
If n is odd, you can replace n with either n + 1 or n - 1.
We have to find the minimum number of replacements needed for n to become 1?
So if the number is 7, then the answer will be 4, as 7 → 8 → 4 → 2 → 1 or 7 → 6 → 3 → 2 → 1
To solve this, we will follow these steps −
ret := 0, n := x
while n > 1
if n is even, then c := n / 2
otherwise when n is even
if n is 3 or n/2 is even, then decrease n by 1, otherwise increase n by 1
increase ret by 1
return ret.
Example (C++)
Let us see the following implementation to get a better understanding −
#include <bits/stdc++.h>
using namespace std;
typedef long long int lli;
class Solution {
public:
int bitCount(int x){
int ret = 0;
while(x){
ret++;
x >>= 1;
}
return ret;
}
int integerReplacement(int x) {
int ret = 0;
lli n = x;
while(n > 1){
if(n % 2 == 0){
n >>= 1;
}
else if(n & 1){
if(n == 3 || (((n >> 1) & 1 )== 0)){
n--;
} else {
n++;
}
}
ret++;
}
return ret;
}
};
main(){
Solution ob;
cout << (ob.integerReplacement(7));
}Input
7
Output
4
Updated on: 02-May-2020
444 Views
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