95. 不同的二叉搜索树 II

95. 不同的二叉搜索树 II

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func generateTrees(n int) []*TreeNode {
    if n <= 0 {
        return nil
    }
    return create(1, n)
}
func create(start, end int) []*TreeNode {
    if start > end {
        return []*TreeNode{nil}
    }
    all_Trees := []*TreeNode{}
    for i := start; i <= end; i++ {
        left_Trees := create(start, i - 1)
        right_Trees := create(i + 1, end)
        for _, left := range(left_Trees) {
            for _, right := range(right_Trees) {
                curTree := &TreeNode{i, nil, nil} 
                curTree.Left = left
                curTree.Right = right
                all_Trees = append(all_Trees, curTree)
            }
        }
    }
    return all_Trees
}