diff options
Diffstat (limited to 'robot_collisions.c')
-rw-r--r-- | robot_collisions.c | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/robot_collisions.c b/robot_collisions.c new file mode 100644 index 0000000..8903992 --- /dev/null +++ b/robot_collisions.c @@ -0,0 +1,98 @@ +// 2751. Robot Collisions +#include "leetcode.h" + +/* + * there are 'n' 1 indexed robots, each having a position on a line, health, and + * movement directions. all robots start moving on the line simultaneously at + * the same speed in their given directions. if two robots ever share the same + * position while moving, they will collide. if two robots collide, the robot + * with lower health is removed from the line and the health of the other robot + * decreases by 1. the surviving robot continues in the same direction it was + * going. if both robots have the same health they are both removed from the + * line. return an array containing the health of the remaining robots after no + * further collisions can occur + */ + +int cmp(const void *a, const void *b) { + int *aa = *(int **)a, *bb = *(int **)b; + return aa[0] - bb[0]; +} + +int *survivedRobotsHealths(int *positions, int positionsSize, int *healths, + int healthsSize, char *directions, int *returnSize) { + int **record = (int **)malloc(sizeof(int *) * positionsSize); + int *stack = (int *)malloc(sizeof(int) * positionsSize), idx = -1; + int *ans = (int *)malloc(sizeof(int) * positionsSize); + *returnSize = 0; + for (int i = 0; i < positionsSize; i++) { + record[i] = (int *)malloc(sizeof(int) * 2); + record[i][0] = positions[i]; + record[i][1] = i; + if (directions[i] == 'L') + healths[i] *= 1; + } + qsort(record, positionsSize, sizeof(int *), cmp); + for (int i = 0; i < positionsSize; i++) { + if (idx == -1) { + stack[++idx] = record[i][1]; + } else if (healths[record[i][1]] < 0 && healths[stack[idx]] > 0) { + if (healths[stack[idx]] == -1 * healths[record[i][1]]) { + healths[stack[idx]] = 0; + healths[record[i][1]] = 0; + idx--; + } else if (healths[stack[idx]] > -1 * healths[record[i][1]]) { + healths[record[i][1]] = 0; + healths[stack[idx]] -= 1; + } else { + while (idx != -1 && healths[stack[idx]] > 0 && + healths[stack[idx]] < -1 * healths[record[i][1]]) { + healths[stack[idx]] = 0; + idx--; + healths[record[i][1]] += 1; + } + if (idx == -1 || healths[stack[idx]] < 0) { + stack[++idx] = record[i][1]; + } else if (-1 * healths[record[i][1]] == healths[stack[idx]]) { + healths[stack[idx]] = 0; + healths[record[i][1]] = 0; + idx--; + } else { + healths[record[i][1]] = 0; + healths[stack[idx]] -= 1; + } + } + } else { + stack[++idx] = record[i][1]; + } + } + for (int i = 0; i < positionsSize; i++) + free(record[i]); + free(record), free(stack); + for (int i = 0; i < positionsSize; i++) + if (healths[i]) + ans[(*returnSize)++] = abs(healths[i]); + return ans; +} + +int main() { + int p1[] = {5, 4, 3, 2, 1}, h1[] = {2, 17, 9, 15, 10}, rs1; + int p2[] = {3, 5, 2, 6}, h2[] = {10, 10, 15, 12}, rs2; + int p3[] = {1, 2, 5, 6}, h3[] = {10, 10, 11, 11}, rs3; + char s1[] = "RRRRR", s2[] = "RLRL", s3[] = "RLRL"; + int *sbh1 = + survivedRobotsHealths(p1, ARRAY_SIZE(p1), h1, ARRAY_SIZE(h1), s1, &rs1); + int *sbh2 = + survivedRobotsHealths(p2, ARRAY_SIZE(p2), h2, ARRAY_SIZE(h2), s2, &rs2); + int *sbh3 = + survivedRobotsHealths(p3, ARRAY_SIZE(p3), h3, ARRAY_SIZE(h3), s3, &rs3); + for (int i = 0; i < rs1; i++) + printf("%d ", sbh1[i]); // expect: 2,17,9,15,10 + printf("\n"); + for (int i = 0; i < rs2; i++) + printf("%d ", sbh2[i]); // expect: 14 + printf("\n"); + for (int i = 0; i < rs3; i++) + printf("%d ", sbh3[i]); // expect: null + printf("\n"); + free(sbh1), free(sbh2), free(sbh3); +} |