[面试] 根据前序和中序重建二叉树，并且中序非递归遍历

#include <iostream>#include <cstring>#include <cstdio>#include <stack>#include <iterator>#include <algorithm>using namespace std;class Node {public :    int value;    Node* lchild;    Node* rchild;    Node(int v) : value(v), lchild(NULL), rchild(NULL) {}    ~Node() {        if(lchild != NULL) delete lchild;        if(rchild != NULL) delete rchild;    }};Node* build(int *pre, int *mid, int n) {    if(pre == NULL || mid == NULL || n <= 0) return NULL;    int rv = pre[0];    Node* root = new Node(rv);    int i;    for(i = 0; i < n && mid[i] != rv; i++);    int leftL = i;    if(leftL > 0) root->lchild = build(pre+1, mid, leftL);    int rightL = n - i - 1;    if(rightL > 0) root->rchild = build(pre+1+leftL, mid+1+leftL, rightL);    return root;}void ino(Node* root) {    if(root == NULL) return;    if(root->lchild) ino(root->lchild);    printf("%d ", root->value);    if(root->rchild) ino(root->rchild);}void fino(Node* root) {    Node* p = root;    stack<Node*> S;    while(1) {        if(p != NULL) {            S.push(p);            p = p->lchild;        }        else {            if(S.empty()) return;            p = S.top();            S.pop();            printf("%d ", p->value);            p = p->rchild;        }    }}int main() {    int preSeq[] = {1, 2, 4, 7, 3, 5, 6, 8};    int inoSeq[] = {4, 7, 2, 1, 5, 3, 8, 6};    Node* root = build(preSeq, inoSeq, 8);    ino(root);    printf("\n");    fino(root);    return 0;}