poj 1331 Multiply

Multiply

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 5179		Accepted: 2773

Description

6*9 = 42" is not true for base 10, but is true for base 13. That is, 6(13) * 9(13) = 42(13) because 42(13) = 4 * 131 + 2 * 130 = 54(10). 

You are to write a program which inputs three integers p, q, and r and determines the base B (2<=B<=16) for which p * q = r. If there are many candidates for B, output the smallest one. For example, let p = 11, q = 11, and r = 121. Then we have 11(3) * 11(3) = 121(3) because 11(3) = 1 * 31 + 1 * 30 = 4(10) and 121(3) = 1 * 32 + 2 * 31 + 1 * 30 = 16(10). For another base such as 10, we also have 11(10) * 11(10) = 121(10). In this case, your program should output 3 which is the smallest base. If there is no candidate for B, output 0. 

Input

The input consists of T test cases. The number of test cases (T ) is given in the first line of the input file. Each test case consists of three integers p, q, and r in a line. All digits of p, q, and r are numeric digits and 1<=p,q, r<=1,000,000.

Output

Print exactly one line for each test case. The line should contain one integer which is the smallest base for which p * q = r. If there is no such base, your program should output 0.

Sample Input

3
6 9 42
11 11 121
2 2 2

Sample Output

13
3
0

题意：给你三个数字p，q，r，问在哪个最小的进制下p*q=r成立；

注意：如果在k进制下p，q，r的每位上的数字应该要小于k；

#include <iostream>
#include <string.h>
using namespace std;
int change(char *a,int k){
	int len=strlen(a);
	int ans=0;
	for (int i=0;i<len;i++){
		ans = ans*k + a[i]-'0';
	}
	return ans;
}
bool isBig(char *a,int k){
	int len=strlen(a);
	for (int i=0;i<len;i++){
		if (a[i]-'0'>=k)
			return false;
	}
	return true;
}
int main(){
	char a[10],b[10],r[10];
	int t,i;
	cin>>t;
	while (t--){
		cin>>a>>b>>r;
		for (i=2;i<=16;i++){
			if (isBig(a,i)==true && isBig(b,i)==true && isBig(r,i)==true){
				int aa = change(a,i);
				int bb = change(b,i);
				int rr = change(r,i);
				long long ans = aa*bb;
				long long ans2 = rr;
				if (ans==ans2)
					break;
			}
			
		}
		if (i==17)
			i=0;
		cout<<i<<endl;
	}
	return 0;
}