NC68 跳台阶

二刷
因为只与前两个有关 所以 不需要一个dp 只需要两个变量

public class Solution {
    public int jumpFloor(int target) {
        int[] dp = new int[target+1];
        for(int i=0;i<=target;i++){
            if(i<=2) dp[i] = i;
            else dp[i] = dp[i-1] +dp[i-2];
        }
        return dp[target];
    }
}

动态规划

public class Solution {
    public int jumpFloor(int target) {
        if(target <=2){
            return target;
        }           
        int pre2 = 1;
        int pre1 = 2;
        for(int i=3; i<=target; i++){
            int cur = pre2 + pre1;
            pre2 = pre1;
            pre1 = cur;
        }
        return pre1;
    }
}