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author | jack <[email protected]> | 2024-06-14 13:13:15 -0600 |
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committer | jack <[email protected]> | 2024-06-14 13:13:15 -0600 |
commit | d343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa (patch) | |
tree | 96df922dae2a5073d9a50ea70c7aae6aa37e3ebe /shortest_path_binary_matrix.c | |
download | leetcode-d343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa.tar.gz leetcode-d343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa.zip |
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Diffstat (limited to 'shortest_path_binary_matrix.c')
-rw-r--r-- | shortest_path_binary_matrix.c | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/shortest_path_binary_matrix.c b/shortest_path_binary_matrix.c new file mode 100644 index 0000000..28da729 --- /dev/null +++ b/shortest_path_binary_matrix.c @@ -0,0 +1,115 @@ +// 1091. Shortest Path in Binary Matrix +#include <assert.h> +#include <stdbool.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +/* + * given an n x n binary matrix 'grid', return the length of the shortest clear + * path in the matrix. if there is no clear path, return -1. a clear path in a + * binary matrix is a path from the top-left cell (ie. 0,0) to the bottom-right + * cell (ie. n - 1, n - 1) such thatyt + * - all the visited cells are of the path 0 + * - all the adjacent cells of the path are 8-directionally connected (ie. they + * are different and they share an edge of a corner) the length of a clear path + * is the number of visited cells of this path + */ + +typedef struct pair { + int x; + int y; +} pair_t; + +typedef pair_t queue_data_t; + +typedef enum queue { + QUEUE_OK, + QUEUE_EMPTY, + QUEUE_FULL, + QUEUE_ERROR = 0xFF +} queue_er_em; + +typedef struct queue_t { + queue_data_t *value; + int buf_size; + int offer_i; + int poll_i; + int cnt; +} queue_t; + +queue_t *create_queue(int buf_size) { + queue_t *q = malloc(sizeof(queue_t)); + memset(q, 0, sizeof(queue_t)); + q->buf_size = buf_size; + q->value = malloc(buf_size * sizeof(queue_data_t)); + memset(q->value, 0, buf_size * sizeof(queue_data_t)); + return q; +} + +queue_er_em offer_queue(queue_t *q, queue_data_t *data) { + assert(q->cnt < q->buf_size); + if (q->cnt >= q->buf_size) + return QUEUE_ERROR; + memcpy(&q->value[q->offer_i++], data, sizeof(queue_data_t)); + if (q->offer_i == q->buf_size) + q->offer_i = 0; + q->cnt++; + return QUEUE_OK; +} + +queue_er_em poll_queue(queue_t *q, queue_data_t *data) { + assert(q->cnt); + if (q->cnt < 1) + return QUEUE_EMPTY; + memcpy(data, &q->value[q->poll_i++], sizeof(queue_data_t)); + if (q->poll_i == q->buf_size) + q->poll_i = 0; + q->cnt--; + return QUEUE_OK; +} + +inline int get_data(queue_t *q) { return q->cnt; } + +bool empty(queue_t *q) { return (q->cnt); } + +int shortestPathBinaryMatrix(int **grid, int grid_size, int *grid_col_size) { + if (grid[0][0] == 1) + return -1; + queue_t *buf = create_queue(500); + int dirr[8][2] = {{-1, -1}, {-1, 0}, {-1, 1}, {0, -1}, + {0, 1}, {1, -1}, {1, 0}, {1, 1}}; + pair_t p = {.x = 0, .y = 0}; + pair_t tmp; + int cnt = 0; + offer_queue(buf, &p); + while (!empty(buf)) { + int c = get_data(buf); + cnt++; + for (int i = 0; i < c; i++) { + poll_queue(buf, &p); + if (p.x == grid_size - 1 && p.y == grid_col_size[0] - 1) + return cnt; + for (int j = 0; j < 8; j++) { + int tr = p.x + dirr[j][0]; + int tc = p.y + dirr[j][1]; + if (tr >= 0 && tr < grid_size && tc >= 0 && tc < grid_col_size[0] && + !grid[tr][tc]) { + tmp.x = tr; + tmp.y = tc; + offer_queue(buf, &tmp); + grid[tr][tc] = -1; + } + } + } + } + return -1; +} + +int main() int g1[2][2] = {{0, 1}, {1, 0}}, gs1 = 2, gcs1[] = { 2, 2 }; +int g2[3][3] = {{0, 0, 0}, {1, 1, 0}, {1, 1, 1}}, gs2 = 3, gcs[] = {3, 3, 3}; +int g3[3][3] = {{1, 0, 0}, {1, 1, 0}, {1, 1, 0}}, gs3 = 3, gc3[] = {3, 3, 3}; +printf("%d\n", shortestPathBinaryMatrix(g1, gs1, gc1)); // expect: 2 +printf("%d\n", shortestPathBinaryMatrix(g2, gs2, gc2)); // expect: 4 +printf("%d\n", shortestPathBinaryMatrix(g3, gs3, gc3)); // expect: -1 +} |