Question Definition
Given a positive integer n and you can do 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. What is the minimum number of replacements needed for n to become 1?
Example 1:
Input:
8
Output:
3
Explanation:
8 -> 4 -> 2 -> 1
Example 2:
Input:
7
Output:
4
Explanation:
7 -> 8 -> 4 -> 2 -> 1
or
7 -> 6 -> 3 -> 2 -> 1
Java Solution
public int integerReplacement(long n) {
if(n <= 1)
return 0;
int result = 0;
if(n % 2 == 0){
while(n % 2 == 0){
n = n / 2;
result++;
}
result = integerReplacement(n) + result;
}else{
result = Math.min(integerReplacement(n + 1), integerReplacement(n - 1)) + 1;
}
return result;
}
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