【LeetCode-106】Construct Binary Tree from Inorder and Postorder Traversal

和LeetCode-105是相同的原理，这次只需要将后续遍历序列从后向前遍历，这道题的关键是递归时参数的设定要想清楚

public class ConstructBinaryTreefromInorderandPostorderTraversa {public class TreeNode {int val;TreeNode left;TreeNode right;TreeNode(int x) {val = x;}}public TreeNode buildTree(int[] inorder, int[] postorder) {return assistBuildTree(inorder,0,inorder.length - 1,postorder,0,postorder.length - 1);    }public TreeNode assistBuildTree(int[] inorder,int ibegin,int iend,int[] postorder,int pbegin,int pend){if (pbegin > pend) {return null;}int povit = postorder[pend];//在中序遍历中找到povit的位置int i = ibegin;for(;i <= iend;i ++){if(inorder[i] == povit){break;}}int rightLength = iend - i;TreeNode root = new TreeNode(povit);//这个参数必须理清楚，理清楚！root.right = assistBuildTree(inorder, i + 1, iend, postorder, pend - rightLength, pend - 1);root.left = assistBuildTree(inorder, ibegin, i - 1, postorder, pbegin, pend - rightLength - 1);return root;}}