Given n, how many structurally unique BST’s (binary search trees) that store values 1…n?

For example,
Given n = 3, there are a total of 5 unique BST's.

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

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