public int climbStairs(int n) {
        int[] previousClimbs = new int[n + 1];
        previousClimbs[0] = 1;
        previousClimbs[1] = 1;
        for(int i = 2; i <= n; i++) {
            previousClimbs[i] = previousClimbs[i -1] + previousClimbs[i - 2];
        }
        
     return previousClimbs[n];
 }