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authorjack <[email protected]>2024-06-14 13:13:15 -0600
committerjack <[email protected]>2024-06-14 13:13:15 -0600
commitd343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa (patch)
tree96df922dae2a5073d9a50ea70c7aae6aa37e3ebe /shortest_path_binary_matrix.c
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+// 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
+}