#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#define NAME "starry"
/* MAXSTAR is the largest a cluster can be */
#define MAXSTAR 160
/* the board */
char board[100][100];
int w, h;
/* clusters already lettered */
int stars[26][MAXSTAR]; /* stars are stored as xval + yval*1000 */
int count[26]; /* number of stars */
int size[26][2]; /* the x & y dimensions */
int nstart; /* number of clusters */
/* the current cluster */
int current[MAXSTAR][2]; /* y, x */
int ncurrent; /* number of stars in current cluster */
/* int_comp is integer comparison, used for bsearch and qsort */
int
int_comp(const void *pa, const void *pb)
{
int a = *(int*)pa;
int b = *(int*)pb;
if (a > b) return 1;
else if (a < b) return -1;
else return 0;
}
/* find the boundary (in my,mx,My, and Mx.. m is minimum, M is maximum */
/* also fills in current */
int
find_boundary(int y, int x, int *my, int *mx, int *My, int *Mx)
{
int rv = 0;
if (board[y][x] != '1') return 0; /* not a star or already visited */
rv++; /* one more star */
board[y][x] = '2'; /* mark as visited */
/* put in current cluster */
current[ncurrent][0] = y;
current[ncurrent][1] = x;
ncurrent++;
/* update boundary */
if (y < *my) *my = y;
if (y > *My) *My = y;
if (x < *mx) *mx = x;
if (x > *Mx) *Mx = x;
/* check all adjacent stars */
if (x > 0)
{
x--;
rv += find_boundary(y, x, my, mx, My, Mx);
if (y > 0) rv += find_boundary(y-1, x, my, mx, My, Mx);
if (y+1 < h) rv += find_boundary(y+1, x, my, mx, My, Mx);
x++;
}
if (y > 0) rv += find_boundary(y-1, x, my, mx, My, Mx);
if (y+1 < h) rv += find_boundary(y+1, x, my, mx, My, Mx);
if (x+1 < w)
{
x++;
rv += find_boundary(y, x, my, mx, My, Mx);
if (y > 0) rv += find_boundary(y-1, x, my, mx, My, Mx);
if (y+1 < h) rv += find_boundary(y+1, x, my, mx, My, Mx);
x--;
}
return rv;
}
/* this is a very basic flood fill
fill ch everywhere there's not a '0' */
void
mark_shape(int y, int x, char ch)
{
if (board[y][x] == ch) return; /* done already */
if (board[y][x] == '0') return; /* nothing to do */
board[y][x] = ch;
/* recurse on all boundary stars */
if (x > 0)
{
x--;
mark_shape(y, x, ch);
if (y > 0) mark_shape(y-1, x, ch);
if (y+1 < h) mark_shape(y+1, x, ch);
x++;
}
if (y > 0) mark_shape(y-1, x, ch);
if (y+1 < h) mark_shape(y+1, x, ch);
if (x+1 < w)
{
x++;
mark_shape(y, x, ch);
if (y > 0) mark_shape(y-1, x, ch);
if (y+1 < h) mark_shape(y+1, x, ch);
}
}
/* is shape id the same as the current shape */
/* specify the orientation with dy/dx and by/bx */
/* dy/dx is the difference value to associate with y and x changes */
/* by/bx is the upper right corner of the bounding box with respect
to the current orientation */
/* NOTE: assumes that the number of stars are the same */
int
check_shape(int id, int dy, int dx, int by, int bx)
{
int lv;
int pval;
for (lv = 0; lv < ncurrent; lv++)
{
pval = (current[lv][0]-by)*dy + (current[lv][1]-bx)*dx;
if (!bsearch(&pval, stars[id], count[id], sizeof(stars[id][0]), int_comp))
return 0; /* found a star that didn't match */
}
return 1;
}
/* we found a star here, make it a cluster */
void
fix_board(int y, int x)
{
int mx, my, Mx, My;
int cnt;
int lv;
int pw, ph;
int f;
/* gather the cluster information */
mx = Mx = x;
my = My = y;
ncurrent = 0;
cnt = find_boundary(y, x, &my, &mx, &My, &Mx);
pw = Mx - mx + 1;
ph = My - my + 1;
f = 0;
/* check each cluster */
for (lv = 0; lv < nstart; lv++)
if (cnt == count[lv]) /* the cluster must have the same # of stars */
{
if (pw == size[lv][1] && ph == size[lv][0])
{ /* the bounding box sizes match */
f += check_shape(lv, 1000, 1, my, mx);
f += check_shape(lv, 1000, -1, my, Mx);
f += check_shape(lv, -1000, 1, My, mx);
f += check_shape(lv, -1000, -1, My, Mx);
}
if (pw == size[lv][0] && ph == size[lv][1])
{ /* the bounding box sizes match */
f += check_shape(lv, 1, 1000, my, mx);
f += check_shape(lv, 1, -1000, my, Mx);
f += check_shape(lv, -1, 1000, My, mx);
f += check_shape(lv, -1, -1000, My, Mx);
}
if (f) break;
}
if (f) mark_shape(y, x, 'a' + lv); /* found match */
else { /* new cluster! */
count[nstart] = 0;
mark_shape(y, x, 'a' + nstart);
for (lv = 0; lv < ncurrent; lv++)
stars[nstart][lv] = (current[lv][0]-my)*1000 + (current[lv][1]-mx);
count[nstart] = ncurrent;
/* we need the stars in increasing order */
qsort(stars[nstart], count[nstart], sizeof(stars[nstart][0]), int_comp);
size[nstart][0] = ph;
size[nstart][1] = pw;
nstart++;
}
}
int
main(int argc, char **argv)
{
//FILE *fin, *fout;
int lv, lv2;
//fin = fopen(NAME ".in", "r");
//fout = fopen(NAME ".out", "w");
//assert(fin);
// assert(fout);
/* read in the data */
scanf ("%d %d", &w, &h);
for (lv = 0; lv < h; lv++) scanf ("%s", board[lv]);
// fclose(fin);
/* everywhere there's a star not in a cluster, make it into one */
for (lv = 0; lv < h; lv++)
for (lv2 = 0; lv2 < w; lv2++)
if (board[lv][lv2] == '1')
fix_board(lv, lv2);
/* output data */
for (lv = 0; lv < h; lv++)
{
printf ("%c", board[lv][0]);
for (lv2 = 1; lv2 < w; lv2++)
printf ("%c", board[lv][lv2]);
printf ( "\n");
}
// fclose(fout);
return 0;
}
修改 usaco 分析的代码
floodfill找出1的区域 在和以前找出的区域 旋转匹配 如果找到则用前面那个编号 找不到则编号加1
posted on 2008-10-11 15:58
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