【LeetCode】70 - Climbing Stairs

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?

Hide Tags: Dynamic Programming

Solution:一个台阶的方法次数为1次，两个台阶的方法次数为2个。n个台阶的方法可以理解成上n-2个台阶，然后2步直接上最后一步；或者上n-1个台阶，再单独上一步

 int climbStairs(int n) {    //Runtime:0ms
     int a=,b=;
     if(n==)return a;
     if(n==)return b;
     int c=;
     for(int i=;i<=n;i++){
         c=a+b;
         a=b;
         b=c;
     }
     return c;
 }
 int climbStairs2(int n){    ////Runtime:0ms
     if(n <= )return n;
     int* step = new int[n];
     step[] = ;
     step[] = ;
     for(int i = ; i < n; i++)step[i] = step[i-] + step[i-];
     return step[n-];
 }