HDU 1710

http://acm.hdu.edu.cn/showproblem.php?pid=1710

题意：给二叉树的先序遍历和中序遍历，确定后序遍历

解法：复习专业课找的一题，根据先序遍历和中序遍历建树，再对树做后序遍历

#include <iostream>
#include <cstdio>

using namespace std;

struct Tree {
Tree *lc, *rc;
int data;
};

Tree *Create(int *preorder, int *inorder, int n) {
for(int i = 0; i < n; i++) {
if(preorder[0] == inorder[i]) {
Tree *node = (Tree*)malloc(sizeof(Tree));
node -> data = preorder[0];
node -> lc = Create(preorder+1, inorder, i);
node -> rc = Create(preorder+i+1, inorder+i+1, n-i-1);
return node;
}
}
return NULL;
}

int rt;

void PostOrder(Tree *root) {
if(root != NULL) {
PostOrder(root -> lc);
PostOrder(root -> rc);
if(root -> data == rt)
printf("%d\n", root->data);
else
printf("%d ", root->data);
}
}

Tree *root;
int preorder[1005], inorder[1005];

int main() {
int n;
while(~scanf("%d", &n)) {
for(int i = 0; i < n; i++)
scanf("%d", &preorder[i]);
for(int i = 0; i < n; i++)
scanf("%d", &inorder[i]);
root = NULL;
rt = preorder[0];
root = Create(preorder, inorder, n);
PostOrder(root);
}
return 0;
}

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