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// 1870. Minimum Speed to Arrive on Time
#include <math.h>
#include <stdio.h>
/*
* given a floating point number 'hour', representing the amount of time you
* have to reach the office. to commute to the office, you must take 'n' trains
* in sequential order. you are also given an integer array 'dist' of length 'n'
* where 'dist[i]' describes the distance in kilometres of the i'th train ride.
* each train can only depart at an integer hour, so you may need to wait in
* between each ride. return the minimum number speed in km/h that all the
* trains must travel at for you to reach the office on time, or '-1' if it is
* possible to be on time.
*/
double hours(int *dist, int dist_size, double hour) {
double res = 0;
for (int i = 0; i < dist_size - 1; i++)
res += ceil(1.0 * dist[i] / hour);
res += (((double)dist[dist_size - 1]) / hour);
return res;
}
int minSpeedOnTime(int *dist, int dist_size, double hour) {
if (hour <= dist_size - 1)
return -1;
int left = 1, right = 1e7, mid, ans;
while (left < right) {
mid = (left + right) / 2;
if (hours(dist, dist_size, mid) <= hour) {
right = mid;
ans = mid;
} else
left = mid + 1;
}
return ans;
}
int main() {
int dist[] = {1, 3, 2}, dist_size = 3;
printf("%d\n", minSpeedOnTime(dist, dist_size, 6)); // expect: 1
printf("%d\n", minSpeedOnTime(dist, dist_size, 2.7)); // expect: 6
printf("%d\n", minSpeedOnTime(dist, dist_size, 1.9)); // expect: -1
}
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