diff options
Diffstat (limited to 'magnetic_force_2_balls.c')
-rw-r--r-- | magnetic_force_2_balls.c | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/magnetic_force_2_balls.c b/magnetic_force_2_balls.c new file mode 100644 index 0000000..4a408b1 --- /dev/null +++ b/magnetic_force_2_balls.c @@ -0,0 +1,43 @@ +// 1552. Magnetic Force Between Two Balls +#include "leetcode.h" + +/* + * in the universe earth c-137 rick discovered a special form of magnetic force + * between two balls if they are put in his new invented basket. rick has 'n' + * empty baskets the i'th basket is at 'position[i]', more has 'm' ball and + * needs to distribute the balls into the baskets such that the minimum magnetic + * force between any two balls is maximum. rick stated that magnetic force + * betweeen two different balls at positions 'x' and 'y' is '|x - y|'. given the + * integer array 'position' and the integer 'm', return the required force. + */ + +int cmp(const void *a, const void *b) { return *(int *)a - *(int *)b; } + +int cnt_ball(int *position, int positionSize, int distance) { + int cnt = 1, ptr = position[0]; + for (int i = 1; i < positionSize; i++) + if (position[i] - ptr >= distance) { + ptr = position[i]; + cnt++; + } + return cnt; +} + +int maxDistance(int *position, int positionSize, int m) { + qsort(position, positionSize, sizeof(int), cmp); + int left = 1, right = position[positionSize - 1], mid; + while (left + 1 < right) { + mid = (left + right) / 2; + if (cnt_ball(position, positionSize, mid) >= m) + left = mid; + else + right = mid - 1; + } + return cnt_ball(position, positionSize, right) >= m ? right : left; +} + +int main() { + int p1[] = {1, 2, 3, 4, 7}, p2[] = {5, 4, 3, 2, 1, 1000000000}; + printf("%d\n", maxDistance(p1, ARRAY_SIZE(p1), 3)); // expect: 3 + printf("%d\n", maxDistance(p2, ARRAY_SIZE(p2), 2)); // expect: 9999999 +} |