java 70.爬楼梯（＃）。java

Posted 2021-05-08

public class Solution {
    private int[] result = new int[1000];
    public int climbStairs(int n) {
        if(n == 1 || n ==2)
            return n;
        result[1] = 1;
        result[2] = 2;
        for(int i = 3;i<=n;i++){
            result[i] = result[i-1] + result[i-2];
        }
        return result[n];
    }
}

public class Solution {
    public int climbStairs(int n) {
        int[] dp = new int[n + 1];
        dp[1] = 1;
        if (n <= 1) return dp[n];
        dp[2] = 2;
        for (int i = 3; i <= n; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        return dp[n];
    }
}