Leetcode (Sword finger offer) - 10- ii Frog jumping on steps

Topic link ： Click to open the link

The main idea of the topic ： A little .

Their thinking ： A little .

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AC Code

• Java

//  Solution (1)
class Solution {
    public int numWays(int n) {
        if (n == 0) return 1;
        int[] dp = new int[n + 1];
        dp[0] = dp[1] = 1;
        for (int i = 2; i <= n; i++) {
            dp[i] = (dp[i - 1] + dp[i - 2]) % 1000000007;
        }
 
        return dp[n];
    }
}

//  Solution (2)
class Solution {
    public int numWays(int n) {
        int a = 1, b = 1, sum;
        for(int i = 0; i < n; i++){
            sum = (a + b) % 1000000007;
            a = b;
            b = sum;
        }
        return a;
    }
}

• C++

class Solution {
public:
    int numWays(int n) {
        int a = 1, b = 1, sum;
        for(int i = 0; i < n; i++){
            sum = (a + b) % 1000000007;
            a = b;
            b = sum;
        }
        return a;
    }
};