// 983. Minimum Cost For Tickets #include #include #include /* * you have planned some train traveling one year in advance. the days of the * year in which you will travel are given as an integer array 'days'. each day * is an integer 1 - 365. train tickets are sold in three different ways: 1 day * pass sold for 'costs[0]' dollars 7 day pass sold for 'costs[1]' dollars 30 * day pass sold for 'costs[2]' dollars the passes allow that many days of * consecutive travel. return mininum number of dollars you need to travel every * day in the given list of days. */ #define MIN(a, b, c) \ ((a) < (b) ? ((a) < (c) ? (a) : (c)) : ((b) < (c) ? (b) : (c))) bool find_item(int *days, int days_size, int target) { int left = 0, right = days_size - 1, mid; while (left <= right) { mid = (left + right) / 2; if (days[mid] == target) return true; if (days[mid] > target) right = mid - 1; else left = mid + 1; } return false; } int mincostTickets(int *days, int days_size, int *costs, int costs_size) { int arr_size = days[days_size - 1] + 30; int *dp = calloc(arr_size, sizeof(int)); for (int i = 30; i < arr_size; i++) { if (find_item(days, days_size, i - 29) == false) dp[i] = dp[i - 1]; else dp[i] = MIN(dp[i - 1] + costs[0], dp[i - 7] + costs[i], dp[i - 30] + costs[2]); } int ans = dp[arr_size - 1]; free(dp); return ans; } int main() { int d1[] = {1, 4, 6, 7, 8, 20}, d2[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31}; int c1[] = {2, 7, 15}; printf("%d\n", mincostTickets(d1, 6, c1, 3)); // expect: 11 printf("%d\n", mincostTickets(d2, 12, c1, 3)); // expect: 11 }