297 - Quadtrees

描述：这道题就是求像素相加问题，给出了两个四叉树的先序输出，构建完这两个四叉树再合并，然后计算像素结果就ok了，注意，像素开始值是1024，也就是说输出如果大于1024就程序错了，关键是能够合并两个四叉树#include <iostream>#include <cstdio>#include <cstring>using namespace std;struct Tnode{    char v;    struct Tnode *first,*second,*third,*fourth;    Tnode ()    {        v=0;        first=second=third=fourth=NULL;    }};int len;Tnode *creat_two_tree(char *b)//创建四叉树{    Tnode *tree=new Tnode;    if(len<strlen(b))    {        tree->v=b[len];        if(b[len]=='p')        {            len++;//注意len++有四个，不是一个            tree->first=creat_two_tree(b);            len++;            tree->second=creat_two_tree(b);            len++;            tree->third=creat_two_tree(b);            len++;            tree->fourth=creat_two_tree(b);        }    }    return tree;}Tnode *creat_new_tree(Tnode *b, Tnode *c)//合并四叉树{    Tnode *tree=new Tnode;    if(b->v=='f'||c->v=='f')tree->v='f';    else if(b->v=='e'&&c->v=='e')tree->v='e';    else    {        tree->v='p';        if(b->v=='p'&&c->v=='p')        {            tree->first=creat_new_tree(b->first,c->first);            tree->second=creat_new_tree(b->second,c->second);            tree->third=creat_new_tree(b->third,c->third);            tree->fourth=creat_new_tree(b->fourth,c->fourth);        }        else if(b->v=='p'&&c->v=='e')        {            tree->first=b->first;            tree->second=b->second;            tree->third=b->third;            tree->fourth=b->fourth;        }        else        {            tree->first=c->first;            tree->second=c->second;            tree->third=c->third;            tree->fourth=c->fourth;        }    }    return tree;}void sum(Tnode *tree,int count)//计算像素值和{    if(tree)    {        if(tree->v=='f')len+=count;        count/=4;        sum(tree->first,count);        sum(tree->second,count);        sum(tree->third,count);        sum(tree->fourth,count);    }}int main(){    //freopen("a.txt","r",stdin);    int n;    char s1[10010],s2[10010];    scanf("%d",&n);    while(n--)    {        memset(s1,0,sizeof(s1));        memset(s2,0,sizeof(s2));        scanf("%s%s",s1,s2);        len=0;        Tnode *root1=creat_two_tree(s1);        len=0;        Tnode *root2=creat_two_tree(s2);        Tnode *root=creat_new_tree(root1,root2);        len=0;        sum(root,1024);        printf("There are %d black pixels.\n",len);    }    return 0;}