Climbing Stairs

70. Climbing Stairs

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Question

Total Accepted: 97743 Total Submissions: 269280 Difficulty: Easy

 

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?

 

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斐波那契数列

class Solution {
public:
    int climbStairs(int n) {
        if (n <= 0) {
            return 0;
        }
        
        int ans = get_ans(n, array);
        
        return ans;
    }
    
    int get_ans(int n, int* array) {
        if (array[n]) {
            return array[n];
        }
        
        if (n == 1) {
            array[1] = 1;
            return 1;
        }
        
        if (n == 2) {
            array[2] = 2;
            return 2;
        }
        
        array[n] = get_ans(n - 1, array) + get_ans(n - 2, array);
        return array[n];
    }
    
    static int array[1000];
};

int Solution::array[1000] = {0};