OJ-Problems-Source/HDOJ/1973_autoAC.cpp
2016-08-19 10:57:19 +08:00

114 lines
2.4 KiB
C++

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <queue>
using namespace std;
struct item
{
int num[4];
} a, b;
int prime[100], primenum, cost[10000];
int toint(item &a)
{
int ans = 0;
for (int i = 0; i < 4; i++)
ans = ans * 10 + a.num[i];
return ans;
}
void makeprime()
{
primenum = 1;
prime[0] = 2;
for (int i = 3; i < 100; i++)
{
bool ok = true;
for (int j = 0; prime[j] * prime[j] <= i; j++)
if (i % prime[j] == 0)
{
ok = false;
break;
}
if (ok)
{
prime[primenum++] = i;
}
}
}
void init()
{
memset(cost, -1, sizeof(cost));
for (int i = 0; i < 4; i++)
{
char ch;
scanf("%c", &ch);
a.num[i] = ch - '0';
}
getchar();
for (int i = 0; i < 4; i++)
{
char ch;
scanf("%c", &ch);
b.num[i] = ch - '0';
}
getchar();
}
bool isprime(int a)
{
for (int i = 0; i < primenum && prime[i] * prime[i] <= a; i++)
if (a % prime[i] == 0)
return false;
return true;
}
void work()
{
cost[toint(a)] = 0;
queue<item> q;
q.push(a);
while (!q.empty())
{
item temp = q.front();
int costnow = cost[toint(temp)];
q.pop();
for (int i = 0; i < 4; i++)
{
int x = temp.num[i];
for (int j = 0; j < 10; j++)
{
if (i == 0 && j == 0)
continue;
if (j == x)
continue;
temp.num[i] = j;
int inttemp = toint(temp);
if (cost[inttemp] == -1 && isprime(inttemp))
{
cost[inttemp] = costnow + 1;
if (inttemp == toint(b))
{
printf("%d\n", cost[inttemp]);
return;
}
q.push(temp);
}
}
temp.num[i] = x;
}
}
}
int main()
{
int t;
makeprime();
scanf("%d", &t);
getchar();
while (t--)
{
init();
if (toint(a) == toint(b))
printf("0\n");
work();
}
return 0;
}