【Leetcode-Easy-70】Climbing Stairs

【Leetcode-Easy-70】Climbing Stairs

题目

You are climbing a stair case. It takes n steps to reach to the top.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Note: Given n will be a positive integer.

思路

斐波那契数列

程序

class Solution {

// public int climbStairs(int n) {
//     if (n <= 2) return n;
//     return climbStairs(n-1) + climbStairs(n-2);
// }

// public int climbStairs(int n) {
//     if (n <= 0) return 0;
//     if (n == 1) return 1;
//     if (n == 2) return 2;
//     return climbStairs(n-1) + climbStairs(n-2);
// }

public int climbStairs(int n) {
if (n <= 2) return n;

int result = 0;

int first = 1;
int second = 2;
for (int i = 3; i <= n; i ++) {
result = first + second;

int temp = first;
first = second;
second = second + temp;

}
return result;
}
}

声明：题目来自Leetcode.