int countBattleships(vector<vector<char>>& board)
{
int m = board.size();
if (m == 0)
{
return 0;
}
int n = board[0].size();
if (n == 0)
{
return 0;
}
vector<int> disjoint_sets;
disjoint_sets.resize(m * n);
for (int i = 0; i < m * n; i++)
{
disjoint_sets[i] = -1;
}
for (int r = 0; r < m - 1; r++)
{
for (int c = 0; c < n - 1; c++)
{
if (board[r][c] == 'X' && board[r + 1][c] == 'X')
{
union_sets(disjoint_sets, r * n + c, (r + 1) * n + c);
}
if (board[r][c] == 'X' && board[r][c + 1] == 'X')
{
union_sets(disjoint_sets, r * n + c, r * n + c + 1);
}
}
if (board[r][n - 1] == 'X' && board[r + 1][n - 1] == 'X')
{
union_sets(disjoint_sets, r * n + (n - 1), (r + 1) * n + (n - 1));
}
}
for (int c = 0; c < n - 1; c++)
{
if (board[m - 1][c] == 'X' && board[m - 1][c + 1] == 'X')
{
union_sets(disjoint_sets, (m - 1) * n + c, (m - 1) * n + c + 1);
}
}
int count = 0;
for (int r = 0; r < m; r++)
{
for (int c = 0; c < n; c++)
{
if (board[r][c] == 'X' && disjoint_sets[r * n + c] < 0)
{
count++;
}
}
}
return count;
}
void solve_case()
{
int i,j,k;
/* 1. construct edges for all pairs of stones */
k = 0;
for (i=0; i<n; i++)
for (j=i+1; j<n; j++)
{
e[k].u = i;
e[k].v = j;
e[k].w = SQR(x[i]-x[j])+SQR(y[i]-y[j]);
k++;
}
/* 2. sort edges by length */
qsort(e,k,sizeof(edge),edgecmp);
/* 3. generate a forest of one tree per stone */
for (i=0; i<n; i++)
make_set(i);
/* 4. while Freddy and Fiona are not in the same tree, add an edge to the forest */
for (i=0; !same_set(0,1); i++)
union_sets(e[i].u,e[i].v);
/* 5. output */
printf("Scenario #%d\n",++scenario);
printf("Frog Distance = %.3f\n\n",sqrt((double)(e[i-1].w)));
}
int main(int argc, char **argv)
{
int i1=1, i2=2, i3=3;
forest_node_t *s1=make_set(&i1), *s2=make_set(&i2), *s3=make_set(&i3);
assert(find_set(s1) == s1);
union_sets(s1, s2);
assert(find_set(s1) == find_set(s2));
assert(find_set(s1) != find_set(s3));
union_sets(s2, s3);
assert(find_set(s1) == find_set(s2) &&
find_set(s1) == find_set(s3));
return 0;
}
void solve()
{
int i, max;
for ( i = 0; i < s.ne; i++ )
if ( !same_component( edges[i].x, edges[i].y ) )
union_sets( edges[i].x, edges[i].y );
max = 1;
for ( i = 0; i < s.nv; i++ )
if ( s.size[i] > max )
max = s.size[i];
printf("%i\n", max );
}
/**
* Runs Kruskal MSF algorithm
* @param el pointer to sorted edge list
* @param fnode_array pointer to forest nodes array
* @param edge_membership designates whether an edge is part of the MSF
*/
void kruskal(edgelist_t *el,
forest_node_t **fnode_array,
unsigned int *edge_membership)
{
unsigned int i;
edge_t *pe;
assert(fnode_array);
assert(edge_membership);
// For each edge, in order by non-decreasing weight...
for ( i = 0; i < el->nedges; i++ ) {
pe = &(el->edge_array[i]);
forest_node_t *set1 = find_set(fnode_array[pe->vertex1]);
forest_node_t *set2 = find_set(fnode_array[pe->vertex2]);
// vertices belong to different forests
if ( set1 != set2 ) {
union_sets(set1, set2);
edge_membership[i] = 1;
}
}
}
