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.
1.递归(超时)
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); }
2.动态规划
public int climbStairs(int n) { if (n == 0 || n == 1 || n == 2) return n; int[] dp = new int[n + 1]; dp[0] = 0; dp[1] = 1; dp[2] = 2; for (int i = 3; i <= n; i++) { dp[i] = dp[i - 1] + dp[i - 2]; } return dp[n]; }
时间: 2024-10-06 17:43:03