package lintCode;

public class BuildTree {

private static TreeNode build(int[] preorder,int ab,int ae,int[] inorder,int bb, int be){

if(ab > ae) return null;

if(ab == ae) return new TreeNode(preorder[ab]);

TreeNode root = new TreeNode(preorder[ab]);

int index = 0;

for(int i = bb; i <= be; i++){

if(inorder[i] == preorder[ab]) index =i;

}

int leftlen = index;

root.left = build(preorder,ab+1,ab+leftlen,inorder,0,index-1);

root.right = build(preorder,index+1,ae,inorder,index+1,be);

return root;

}

public static TreeNode buildTree(int[] preorder, int[] inorder) {

return build(preorder,0,preorder.length-1,inorder,0,inorder.length-1);

}

public static void main(String[] args) {

int[] a = {1,2,3};

int[] b = {3,2,1};

buildTree(a, b);

}

}