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-rw-r--r--jump_game4.c97
1 files changed, 97 insertions, 0 deletions
diff --git a/jump_game4.c b/jump_game4.c
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+// 1345. Jump Game IV
+#include "lib/uthash/src/uthash.h"
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * given array of integers 'arr', you are initially positioned at first index of
+ * array. in one step, you can jump from index 'i' to index 'j'. return minimum
+ * number of steps to reach lat index of array. notice, you cannot jump outside
+ * of array at any time.
+ */
+
+typedef struct {
+ int key;
+ struct list_node *ptr;
+ UT_hash_handle hh;
+} node;
+
+typedef struct {
+ int val;
+ int *next;
+} list_node;
+
+typedef struct {
+ int pos;
+ int step;
+} status;
+
+int minJumps(int *arr, int arr_size) {
+ if (arr_size <= 1)
+ return 1;
+ status obj[arr_size];
+ int visited[arr_size];
+ memset(visited, 0, arr_size * sizeof(int));
+ node *hash = NULL, *s;
+ struct list_node *tp;
+ for (int i = 0; i < arr_size; i++) {
+ HASH_FIND_INT(hash, &arr[i], s);
+ if (!s) {
+ s = (node *)calloc(1, sizeof(node));
+ s->key = arr[i];
+ HASH_ADD_INT(hash, key, s);
+ }
+ tp = (struct list_node *)calloc(1, sizeof(struct list_node));
+ tp->val = i;
+ tp->next = s->ptr;
+ s->ptr = tp;
+ }
+ int top = 1, left = 0, pos, val;
+ obj[0].step = obj[0].pos = 0;
+ visited[0] = 1;
+ while (left < top) {
+ if (obj[left].pos == arr_size - 1)
+ break;
+ val = arr[obj[left].pos];
+ HASH_FIND_INT(hash, &val, s);
+ if (s) {
+ tp = s->ptr;
+ while (tp) {
+ pos = tp->val;
+ if (!visited[pos]) {
+ visited[pos] = 1;
+ obj[top].step = obj[left].step + 1;
+ obj[top].pos = pos;
+ top++;
+ }
+ tp = tp->next;
+ }
+ HASH_DEL(hash, s);
+ }
+ for (int i = 0; i < 2; i++) {
+ pos = obj[left].pos + (i ? 1 : -1);
+ if (pos < 0 || pos >= arr_size)
+ continue;
+ if (visited[pos])
+ continue;
+ obj[top].step = obj[left].step + 1;
+ obj[top].pos = pos;
+ visited[pos] = 1;
+ top++;
+ }
+ left++;
+ }
+ free(tp);
+ return obj[left].step;
+}
+
+int main() {
+ int a1[] = {100, -23, -23, 404, 100, 23, 23, 23, 3, 404};
+ int a2[] = {7};
+ int a3[] = {7, 6, 9, 6, 9, 6, 9, 7};
+ printf("%d\n", minJumps(a1, sizeof(a1) / sizeof(a1[0]))); // expect: 3
+ printf("%d\n", minJumps(a2, sizeof(a2) / sizeof(a2[0]))); // expect: 0
+ printf("%d\n", minJumps(a3, sizeof(a3) / sizeof(a3[0]))); // expect: 1
+}