題目描述 輸入某二叉樹的前序遍歷和中序遍歷的結果，請重建出該二叉樹。假設輸入的前序遍歷和中序遍歷的結果中都不含重復的數字。例如輸入前序遍歷序列{1,2,4,7,3,5,6,8}和中序遍歷序列{4,7,2,1,5,3,8,6}，則重建二叉樹并返回。
public class Solution { public TreeNode reConstructBinaryTree(int [] PRe,int [] in) { return BuildTree(pre, in, 0, pre.length-1, 0, in.length-1); } public TreeNode BuildTree(int [] pre, int [] in, int preSt, int preEn, int inSt, int inEn){ if(preSt > preEn || inSt > inEn){ return null; } TreeNode treeNode = new TreeNode(pre[preSt]); for (int i=inSt; i<=inEn; i++){ if(pre[preSt] == in[i]){ treeNode.left = BuildTree(pre, in, preSt+1, preEn, inSt, i-1); treeNode.right = BuildTree(pre, in, preSt+1+i-inSt,preEn,i+1, inEn); } } return treeNode; }}新聞熱點
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