Climbing Stairs Problem
Description
LeetCode Problem 70.
You are climbing a staircase. It takes n steps to reach the top.
Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
Example 1:
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Input: n = 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps
Example 2:
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Input: n = 3
Output: 3
Explanation: There are three ways to climb to the top.
1. 1 step + 1 step + 1 step
2. 1 step + 2 steps
3. 2 steps + 1 step
Constraints:
- 1 <= n <= 45
Sample C++ Code
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class Solution {
public:
int climbStairs(int n) {
int f1 = 1;
int f2 = 2;
if (n == 1)
return f1;
if (n == 2)
return f2;
int f;
for (int i = 3; i <= n; i ++) {
f = f1 + f2;
f1 = f2;
f2 = f;
}
return f;
}
};