题目

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思路

  • 该题与爬楼梯一样

    代码

    1.   public int numWays(int n) {
    2.       if (n == 0 || n == 1) return 1;
    3.       if (n == 2) return 2;
    4.       int p1 = 1, p2 = 2;
    5.       for (int i = 3; i <= n; i++) {
    6.           int p = (p1 + p2) % 1000000007;
    7.           p1 = p2;
    8.           p2 = p;
    9.       }
    10.       return p2;
    11.   }
    青蛙跳台阶问题