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// 554. Brick Wall
#include "leetcode.h"
/*
* there is a rectangular brick wall in front of you with 'n' rows of bricks.
* the i'throw has some number of bricks each of the same height (ie. one unit)
* butthey can be of different widths. the total width of each row is the same.
* draw a vertical line from the top to the bottom and cross the least bricks.
* if your line goes through the edge of a brick, then the brick is not
* considered as crossed. you cannot draw a line just along one of the two
* vertical edges of the wall, in which case the line will obviously cross no
* bricks. given the 2d array 'wall' that contains the information about the
* wall, return the minimum number of cross bricks after drawing such a vertical
* line
*/
#define MOD 1009
struct item {
struct item *next;
int key;
int freq;
};
static struct item *hash[MOD];
void hash_init(void) { memset((void *)hash, 0, sizeof(hash)); }
int hash_get(int key, int *freq) {
int idx = key % MOD;
for (struct item *header = hash[idx]; header; header = header->next)
if (header->key == key) {
*freq = header->freq;
return 0;
}
return -1;
}
void hash_set(int key, int freq) {
struct item *i = (struct item *)malloc(sizeof(struct item));
i->key = key;
i->freq = freq;
i->next = hash[key % MOD];
hash[key % MOD] = i;
}
void hash_free(void) {
for (int i = 0; i < MOD; i++)
for (struct item *header = hash[i], *delete; header;) {
delete = header;
header = header->next;
free(delete);
}
}
int leastBricks(int **wall, int wallSize, int *wallColSize) {
int ans = 0, freq;
hash_init();
for (int i = 0; i < wallSize; i++)
for (int j = 0, end = 0; j < wallColSize[i] - 1; j++) {
end += wall[i][j];
if (hash_get(end, &freq) == -1)
freq = 1;
else
freq++;
hash_set(end, freq);
if (freq > ans)
ans = freq;
}
hash_free();
return wallSize - ans;
}
int main() {
int w1i[6][4] = {{1, 2, 2, 1}, {3, 1, 2}, {1, 3, 2},
{2, 4}, {3, 1, 2}, {1, 3, 1, 1}},
w2i[3][1] = {{1}, {1}, {1}};
struct two_d_arr w1, w2;
two_d_arr_init(&w1, 6, 4, w1i);
two_d_arr_init(&w2, 3, 1, w2i);
printf("%d\n", leastBricks(w1.arr, w1.row_size, w1.col_size)); // expect: 2
printf("%d\n", leastBricks(w2.arr, w2.row_size, w2.col_size)); // expect: 3
two_d_arr_free(&w1);
two_d_arr_free(&w2);
}
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