【POJ】3076 Sudoku

#include<cstdio>
#include<cstring>
#define INF 0x7FFFFFFF
#define MAXS 16
#define MAXH 4100
#define MAXL 1025
#define MAXN 4200000
char sd[MAXS][MAXS];
int L[MAXN], R[MAXN], U[MAXN], D[MAXN], C[MAXN], X[MAXN];
int size, S[MAXL], H[MAXH], Q[MAXH];
bool vis[MAXH];
bool Read()
{
int i, j;
for (i = 0; i < MAXS; i++)
{
for (j = 0; j < MAXS; j++)
{
if (scanf(" %c", &sd[i][j]) == EOF)
return false;
}
}
return true;
}
void Init()
{
int i;
for (i = 0; i < MAXL; i++)
{
R[i] = i + 1;
L[i + 1] = i;
U[i] = D[i] = i;
S[i] = 0;
}
R[MAXL - 1] = 0;
size = MAXL;
}
void Remove(int c)
{
int i, j;
L[R[c]] = L[c];
R[L[c]] = R[c];
for (i = D[c]; i != c; i = D[i])
{
for (j = R[i]; j != i; j = R[j])
{
U[D[j]] = U[j];
D[U[j]] = D[j];
S[C[j]]--;
}
}
}
void Resume(int c)
{
int i, j;
L[R[c]] = c;
R[L[c]] = c;
for (i = D[c]; i != c; i = D[i])
{
for (j = R[i]; j != i; j = R[j])
{
U[D[j]] = j;
D[U[j]] = j;
S[C[j]]++;
}
}
}
inline void Link(int r, int c)
{
D[size] = D[c];
U[size] = c;
U[D[c]] = size;
D[c] = size;
if (H[r] < 0)
H[r] = L[size] = R[size] = size;
else
{
L[size] = H[r];
R[size] = R[H[r]];
L[R[H[r]]] = size;
R[H[r]] = size;
}
S[c]++;
X[size] = r;
C[size++] = c;
}
bool Dance()
{
if (R[0] == 0)
return true;
int i, j, temp, c;
for (temp = INF,i = R[0]; i; i = R[i])
{
if (temp > S[i])
{
temp = S[i];
c = i;
}
}
Remove(c);
for (i = D[c]; i != c; i = D[i])
{
vis[X[i]] = true;
for (j = R[i]; j != i; j = R[j])
Remove(C[j]);
if (Dance())
return true;
for (j = L[i]; j != i; j = L[j])
Resume(C[j]);
vis[X[i]] = false;
}
Resume(c);
return false;
}
int main()
{
int i, j, k, r;
while (Read())
{
Init();
for (i = r = 0; i < MAXS; i++)
{
for (j = 0; j < MAXS; j++)
{
if (sd[i][j] == '-')
{
for (k = 0; k < MAXS; k++)
{
H[++r] = -1;
Q[r] = k;
Link(r, (i << 4) + k + 1);
Link(r, 256 + (j << 4) + k + 1);
Link(r,    512 + ((((i >> 2) << 2) + (j >> 2)) << 4) + k + 1);
Link(r, 768 + (i << 4) + j + 1);
}
}
else
{
k = sd[i][j] - 'A';
H[++r] = -1;
Q[r] = k;
Link(r, (i << 4) + k + 1);
Link(r, 256 + (j << 4) + k + 1);
Link(r, 512 + ((((i >> 2) << 2) + (j >> 2)) << 4) + k + 1);
Link(r, 768 + (i << 4) + j + 1);
}
}
}
memset(vis, false, sizeof(vis));
Dance();
for (k = 0, i = 1; i <= r; i++)
{
if (vis[i])
{
k++;
putchar('A' + Q[i]);
if (k % 16 == 0)
putchar('\n');
}
}
putchar('\n');
}
return 0;
}