Проще нарисовать, чем объяснить ...
2 2 2 2 1 => A A A A B => (A: 4, B: 1)
1 2 2 2 1 => C A A A B => (A: 3 + 4, B: 1 + 1, C: 1)
3 3 2 3 2 => D D A E F => (A: 1 + 7, B: 2, C: 1, D: 2, E: 1, F: 1)
3 1 3 3 1 => D G E E G => (A: 8, B: 2, C: 1, D: 2 + 1, E: 2 + 1, F: 1, G: 1)
1 1 2 3 1 => ...
1 3 1 3 3 => ...
обновление
А теперь с реальным кодом:
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#define ROWS 6
#define COLS 5
unsigned char eles[ROWS][COLS] = { { 2, 2, 2, 2, 1 },
{ 1, 2, 2, 2, 1 },
{ 3, 3, 2, 3, 2 },
{ 3, 1, 3, 3, 1 },
{ 1, 1, 2, 3, 1 },
{ 1, 3, 1, 3, 3 } };
struct zone {
int acu;
int row, col;
int refs;
};
typedef struct zone zone;
zone *
new_zone(int row, int col) {
zone *z = (zone *)malloc(sizeof(zone));
z->col = col;
z->row = row;
z->refs = 1;
z->acu = 0;
}
void croak (const char *str) {
fprintf(stderr, "error: %s\n", str);
exit(1);
}
void
free_zone(zone *z) {
if (z->refs != 0) croak("free_zone: reference count is not cero");
free(z);
}
zone *
ref_zone(zone *z) {
z->refs++;
return z;
}
void
unref_zone(zone *z) {
z->refs--;
if (!z->refs) free_zone(z);
}
int
main() {
zone *last[COLS];
zone *current[COLS];
zone *best = new_zone(0, 0);
int i, j;
memset(last, 0, sizeof(last));
for (j = 0; j < ROWS; j++) {
for (i = 0; i < COLS; i++) {
unsigned int ele = eles[j][i];
zone *z;
/* printf("analyzing ele: %d at row %d, col: %d\n", ele, j, i); */
if (i && (ele == eles[j][i-1])) {
/* printf(" equal to left element\n"); */
z = ref_zone(current[i-1]);
if (j && (ele == eles[j-1][i])) {
zone *z1 = last[i];
/* printf(" equal to upper element\n"); */
if (z != z1) {
int k;
/* printf(" collapsing zone %p\n", z1); */
z->acu += z1->acu;
for (k = 0; k < COLS; k++) {
if (last[k] == z1) {
last[k] = ref_zone(z);
unref_zone(z1);
}
}
for (k = 0; k < i; k++) {
if (current[k] == z1) {
current[k] = ref_zone(z);
unref_zone(z1);
}
}
}
}
}
else if (j && (ele == eles[j-1][i])) {
/* printf(" equal to upper element\n"); */
z = ref_zone(last[i]);
}
else {
/* printf(" new element\n"); */
z = new_zone(j, i);
}
z->acu++;
current[i] = z;
/* printf(" element zone: %p\n", z); */
}
for (i = 0; i < COLS; i++) {
if (j) unref_zone(last[i]);
last[i] = current[i];
if (best->acu < current[i]->acu) {
unref_zone(best);
best = ref_zone(current[i]);
/* printf("best zone changed to %p at row; %d, col: %d, acu: %d\n", best, best->row, best->col, best->acu); */
}
}
}
printf("best zone is at row: %d, col: %d, ele: %d, size: %d\n", best->row, best->col, eles[best->row][best->col], best->acu);
}