Jokewithpermutation
Joey had saved a permutation of integers from 1 to n in a text file. All the numbers were written asdecimal numbers without leading spaces.
Then Joe made a practical joke on her: he removed all the spaces in the file.
Help Joey to restore the original permutation after the Joe’s joke!
Input
The input file contains a single line with a single string — the Joey’s permutation without spaces.
The Joey’s permutation had at least 1 and at most 50 numbers.
Output
Write a line to the output file with the restored permutation. Don’t forget the spaces!
If there are several possible original permutations, write any one of them.
Sample input and output
4111109876532
4 1 11 10 9 8 7 6 5 3
https://vjudge.net/contest/328613#problem/J
題意：n個數（n<=50）寫在一行，之間的空格被去掉，要求復原
dfs找合適的情況，每次在一個數後面加空格或在兩個數後面加空格
#include <bits/stdc++.h>
char s[250];
int len,num;
int dfs(int n,int flag[51])
{
if(n == -1)
return 1;
int numm = s[n]-'0';
if(s[n]!='0'&&numm <= num&&!flag[numm])
{
flag[numm] = 1;
if(dfs(n-1,flag))
{
if(n == 0)
printf("%c",s[n]);
else
printf(" %c",s[n]);
return 1;
}
flag[numm] = 0;
}
if(n >=1)
{
numm = (s[n-1]-'0')*10+s[n]-'0';
if(s[n-1]!='0'&&numm <= num&&!flag[numm])
{
flag[numm] = 1;
if(dfs(n-2,flag))
{
if(n-1==0)
printf("%c%c",s[n-1],s[n]);
else
printf(" %c%c",s[n-1],s[n]);
return 1;
}
flag[numm] = 0;
}
}
return 0;
}
void init()
{
freopen("joke.in", "r", stdin);
freopen("joke.out", "w", stdout);
}
int main()
{
//init();
int flag[56];
scanf("%s",s);
len = strlen(s);
if(len <= 9)
num = 9;
else
{
num = (len-9)/2+9;
}
memset(flag,0,sizeof(flag));
dfs(len-1,flag);
printf("\n");
return 0;
}