HDU 4474 Yet Another Multiple Problem ( BFS + 同余剪枝 )

没什么巧办法，直接搜就行。

用余数作为每个节点的哈希值。

#include <cstdio>
#include <cstring>
#include <cstdlib>

const int MAXN = 10100;

struct node
{
int mod;
int fa;
int digit;
node() {}
node( int mod, int fa, int dig ):mod(mod), fa(fa), digit(dig) { }
};

int N;
bool ok[12];
bool vis[MAXN];
node Q[MAXN << 2];

void findFa( int u )
{
if ( u == -1 ) return;
findFa( Q[u].fa );
printf( "%d", Q[u].digit );
}

int BFS()
{
int head = 0;
int tail = 0;
memset( vis, false, sizeof(vis) );

for ( int i = 1; i < 10; ++i )
{
if ( !ok[i] ) continue;
int hashh = i % N;
if ( vis[hashh] ) continue;
vis[hashh] = true;
Q[tail] = node( hashh, -1, i );
if ( hashh == 0 ) return tail;
++tail;
}

while ( head < tail )
{
node cur = Q[head];
for ( int i = 0; i < 10; ++i )
{
if ( !ok[i] ) continue;
int hashh = ( cur.mod * 10 + i ) % N;

if ( vis[hashh] ) continue;
vis[hashh] = true;
Q[tail] = node( hashh, head, i );
if ( hashh == 0 ) return tail;
++tail;
}
++head;
}
return -1;
}

int main()
{
int cas = 0;
while ( scanf( "%d", &N ) == 1 )
{
memset( ok, true, sizeof(ok) );
int n;
scanf( "%d", &n );
for ( int i = 0; i < n; ++i )
{
int digit;
scanf( "%d", &digit );
ok[digit] = false;
}

printf( "Case %d: ", ++cas );
int ans = BFS();
if ( ans != -1 ) findFa( ans );
else printf("-1");

puts("");
}
return 0;
}

转载于:https://www.cnblogs.com/GBRgbr/p/3360143.html