【leetcode】第70题 Climbing Stairs 题目+解析+JAVA代码

【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.

【解析】

这个题其实是一个斐波那契数列，第n个台阶可以由第n-1个台阶一次走一步，也可以第n-2个台阶一次走两步，所以mem[n]=mem[n-1]+mem[n-2]

【代码】

 public int climbStairs(int n) {
        if(n == 0 || n == 1 || n == 2){return n;}
        int[] mem = new int[n];
        mem[0] = 1;
        mem[1] = 2;
        for(int i = 2; i < n; i++){
            mem[i] = mem[i-1] + mem[i-2];
        }
        return mem[n-1];
    }