leetcode 096 Unique Binary Search Trees

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.

1         3     3      2      1
\       /     /      / \      \
3     2     1      1   3      2
/     /       \                 \
2     1         2                 3

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class Solution {
public:
int numTrees(int n) {
if(n==1||n==0) return 1;
if(n==2) return 2;

int *dp=new int[n+1];
dp[0] = 1;
dp[1] = 1;
dp[2] = 2;

for(int i=3; i <= n; i++) {
dp[i] = 0;
for(int j=0; j<=i-1; j++) {
dp[i] += (dp[i-1-j]*dp[j]);
}
}
return dp
;
}
};