Leetcode 96. Unique Binary Search Trees 50.1% Medium

진짜 재수없는 문제 정답률 50.1% Medium

 

스터디 Tree 문제5번 백준 34단계정도

 

http://www.goodtecher.com/leetcode-144-binary-tree-preorder-traversal/

 

class Solution {
    public int numTrees(int n) {
        int[] ans = new int[n+1];
        ans[0] = ans[1] = 1;
        for(int i=2;i<=n;i++){
            for(int j=1;j<=i;j++){
                ans[i] += ans[j-1]*ans[i-j]; 
            }
        }
        return ans[n];
    }
}