#include <cstdlib>#include <cstdio>#include <iostream>#include <cstring>using namespace std;/* Author: YuXun Lu Time:23rd/2/2012 Last Time:About 7 Hours Begin Time:Unknown End Time:Unknown Test Data: ABDKQOPENLMCFIGHJ QKPODBNEMLACIFGJH 输出： 随便找一个AC过得程序测一下就好 思路： 以前序遍历的第一个元素将中序遍历的数组分成两个部分 [0..root)和(root,len-1] 有一个当前指针p，从1开始一直到len1-1遍历前序数组。 p指向当前在中序遍历搜索的元素。 有一个node数组，保存左右儿子的下标、自己的val在中序遍历数组 中的位置还有一个val Search_Left(int begin,int end,char val) t = search(begin,end,val) //在中序数组里搜索当前要搜索的节点 if( t != -1 ) 找到了 { nodes[end].l = t; p++ //搜索找到的这个节点的左、右儿子，注意， Search_Left的end是父节点的位置， Search_Right的begin是父节点的位置 Search_Left(begin,nodes[t].pos,buf1[p]); Search_Right(nodes[t].pos,end,buf1[p]); } Search_Right(int begin,int end,char val) { t = Search(begin,end,val) if ( t != -1) { nodes[begin].r = t; p++; search_left(begin,nodes[t].pos,buf1[p]); search_right(nodes[t].pos,end,buf1[p]); } } 注意，必须先搜左边的再搜右边的 因为每次搜索的区间都不一样，最好自己构建一棵树写一下这个 过程，区间的两个端点是有继承性的。*/const int MAX_SIZE = 1000;struct node{ int l; // the index of node in node int r; char val; int pos;};char buf1[MAX_SIZE];char buf2[MAX_SIZE];int len1 = 0 ,len2 = 0,p;node nodes[MAX_SIZE];void left_search(int begin,int end,char val);void right_search(int begin,int end,char val);int search(int begin,int end,char val);void DFS(node now){ if(now.l != -1) DFS(nodes[now.l]); if(now.r != -1) DFS(nodes[now.r]); printf("%c",now.val);}int search1(int begin,int end,char val){ int res = -1; for(int i = begin;i < end; i++) { if ( val == buf1[i]) res = i; } return res;}void left_search(int begin,int end,char val){ int t; if(begin >= end) return;#ifdef DBG printf("Search left son for %c\n",nodes[end].val);#endif t = search(begin,end,val); if( t != -1) { ///找到了#ifdef DBG printf("Gotted!Val is %c\n",buf2[t]);#endif nodes[end].l = t; p++; ///找下一个元素 left_search(begin,nodes[t].pos,buf1[p]); right_search(nodes[t].pos,end,buf1[p]); }}void right_search(int begin,int end,char val){ int t; if(begin >= end) return;#ifdef DBG printf("Search right son for %c\n",nodes[begin].val);#endif t = search(begin,end,val); if( t != -1) {#ifdef DBG printf("Gotted!The val is %c\n",buf2[t]);#endif nodes[begin].r = t; p++; // right_search(nodes[t].pos,end,buf1[p]); left_search(begin,nodes[t].pos,buf1[p]); right_search(nodes[t].pos,end,buf1[p]); }}int search(int begin,int end,char val){ int res = -1; for(int i = begin; i < end; i++) { if(buf2[i] == val) { res = i;break; } } return res;}int main(int argc,char* argv[]){ #ifdef INPUT freopen("B:\\acm\\poj2255-Tree Recovery\\input.txt","r",stdin); #endif while(scanf("%s",buf1) != EOF) { int root = 0; memset(nodes,0,sizeof(node)*MAX_SIZE); p = 0; scanf("%s",buf2); len1 =strlen(buf1);len2 = strlen(buf2); for(int i = 0 ; i < len1 ; i++) { nodes[i].val = buf2[i]; nodes[i].l = -1; nodes[i].r = -1; nodes[i].pos = i; } root = search(0,len2,buf1[0]); p = 1; left_search(0,root,buf1[p]); right_search(root,len2,buf1[p]); DFS(nodes[root]); memset(buf1,0,sizeof(char)*MAX_SIZE); memset(buf2,0,sizeof(char)*MAX_SIZE); printf("\n"); } return 0;}
