POJ 1416 Shredding Company

　　给出一个Max 和一串数字。将这一串数字分割成若干个数，其和为sum。求最接近但不超过Max的sum。。。

　　将这个sum及这若干个数输出来。

　　DFS + 打印路径

　　

#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <cstring>
#include <cstdio>

using namespace std;

char SNum[10];

struct N
{
    int data,ans,pre;
    N *l,*r;
}*root;

N *creat()
{
    N *p = (N *)malloc(sizeof(N));
    p->l = p->r = NULL;
    return p;
}

struct P
{
    int site,pre;
}path[100000];

int top;

void insert(N *&root,int data,int pre)
{
    if(root == NULL)
    {
        root = creat();
        root->ans = 1;
        root->pre = pre;
        root->data = data;
        return ;
    }
    if(data < root->data)
        insert(root->l,data,pre);
    else if(data > root->data)
        insert(root->r,data,pre);
    else root->ans++;
}

void dfs(int sum,int Max,char *s,int site,int pre)
{
    if(sum > Max)
        return ;

    if(strlen(s) == 0)
    {
        if(sum <= Max)
        {
            insert(root,sum,pre);
        }
        return ;
    }

    int i,dec,j,temp,len;

    for(i = 0,len = strlen(s);i < len; ++i)
    {
        for(j = i,temp = 0,dec = 1;j >= 0; --j,dec *= 10)
            temp += (s[j]-'0')*dec;

        path[top].pre = pre;
        path[top].site = site;
        top++;

        dfs(sum+temp,Max,s+i+1,site+i+1,top-1);
    }
}

void PrintPath(int pre)
{
    int s[100],top = 0;
    while(pre != -1)
    {
        s[top++] = path[pre].site;
        pre = path[pre].pre;
    }

    for(int i = top-1;i >= 0; --i)
    {
        printf(" ");
        if(i != 0)
        {
            for(int j = s[i];j < s[i-1]; ++j)
                printf("%c",SNum[j+1]);
        }
        else
        {
            for(int j = s[i]+1; SNum[j] != ''; ++j)
                printf("%c",SNum[j]);
        }
    }
    puts("");
}

void SeekMax(N *root)
{
    if(root->r != NULL)
        SeekMax(root->r);
    else
    {
        if(root->ans == 1)
        {
            printf("%d",root->data);
            PrintPath(root->pre);
        }
        else
            printf("rejected
");
    }
}

int main()
{
    int Max,sum,j,i,len,dec;

    while(scanf("%d %s",&Max,SNum+1) && (Max != 0 || strcmp(SNum+1,"0") != 0))
    {
        root = NULL;

        top = 0;

        for(i = 1,len = strlen(SNum+1);i <= len; ++i)
        {
            for(j = i,dec = 1,sum = 0;j >= 1; --j,dec *= 10)
                sum += (SNum[j]-'0')*dec;
            path[top].pre = -1;
            path[top].site = 0;
            top++;
            dfs(sum,Max,SNum+1+i,i,top-1);
        }
        if(root == NULL)
            cout<<"error"<<endl;
        else
            SeekMax(root);
    }
    return 0;
}

　　今天拿到的第三个1A。。。。再用DFS写打印路径的题就剁手。。。