HDU 1710-Binary Tree Traversals

好久没好好AC了， 这学期的数据结构也没好好学。恶补ing...

 

题目大意：告诉二叉树的先序序列和中序序列，求后序序列。

思路：先序建立二叉链表，再后续遍历二叉树。

 

#include <cstdio>using namespace std;typedef struct Binary{ int data; Binary *lchild, *rchild; Binary() { lchild = NULL; rchild = NULL; }}*BitTree;int pre[1010], in[1010];void Build(BitTree &root, int len, int pst, int ped, int inst, int ined)//先序建树{ int i, l_len = 0; if (len <= 0) return ; root = new Binary; root->data = pre[pst]; for (i = inst; i <= ined; i++) { if (in[i] == pre[pst]) { l_len = i - inst; break; } } Build(root->lchild, l_len, pst+1, pst+l_len, inst, i-1); Build(root->rchild, len-1-l_len, pst+l_len+1, ped, i+1, ined); }void Travel(Binary *root)//后序遍历{ int i; if (root) { Travel(root->lchild); Travel(root->rchild); printf("%d ", root->data); }}int main(){ int i, n; BitTree root; while (scanf("%d", &n) != EOF) { for (i = 0; i < n; i++) { scanf("%d", &pre[i]); } for (i = 0; i < n; i++) { scanf("%d", &in[i]); } Build(root, n, 0, n-1, 0, n-1); Travel(root->lchild); Travel(root->rchild); printf("%d/n", root->data); } return 0;}