Problem:
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
思路：
Solution (C++):
unordered_map<int, int> visited;
int integerReplacement(int n) {
if (n == 1) return 0;
if (visited.count(n) == 0) {
if (n & 1 == 1)
visited[n] = 2 + min(integerReplacement(n/2), integerReplacement(n/2+1));
else
visited[n] = 1 + integerReplacement(n/2);
}
return visited[n];
}
性能：
Runtime: 0 ms Memory Usage: 9.7 MB
思路：
Solution (C++):
性能：
Runtime: ms Memory Usage: MB
