Description
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:
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:
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
Solution
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int climbStairs(int n){
if (n <= 3)
return n;
int a = 1, b = 1;
for (int i = 2; i <= n; i++) {
int c = a + b;
a = b;
b = c;
}
return b;
}
Runtime: 0 ms, faster than 100.00% of C online submissions for Climbing Stairs.
Memory Usage: 5.7 MB, less than 22.38% of C online submissions for Climbing Stairs.
