poj 1426 Find The Multiple (簡單搜尋dfs)
題目:
Given a positive integer n, write a program to find out a nonzero multiple m of n whose decimal representation contains only the digits 0 and 1. You may assume that n is not greater than 200 and there is a corresponding m containing no more than 100 decimal digits.
Input
The input file may contain multiple test cases. Each line contains a value of n (1 <= n <= 200). A line containing a zero terminates the input.
Output
For each value of n in the input print a line containing the corresponding value of m. The decimal representation of m must not contain more than 100 digits. If there are multiple solutions for a given value of n, any one of them is acceptable.
Sample Input
2 6 19 0
Sample Output
10 100100100100100100 111111111111111111
題意:
本題要找出數m,m是隻有0和1構成的十進位制數,並且是n的倍數,若有多個答案,輸出任意一個就可以。
題解:
經過思考會發現m最大不會超過unsigned long long 的範圍,所以用unsigned long long儲存就可以,接下來就是深搜就ok。
程式碼:
#include <iostream> using namespace std; unsigned long long ans; bool f; void dfs(unsigned long long s,int n,int k) { if(f) return ; if(s%n==0) {ans=s;f=true; return ;} if(k==19) return ; //如果k超過19就不在unsigned long long的範圍內了 dfs(s*10,n,k+1); dfs(s*10+1,n,k+1); return ; } int main() { int n; while(cin>>n,n) { ans=0; f=false; dfs(1,n,0); cout<<ans<<endl; } return 0; }