Question

1450. Number of Students Doing Homework at a Given Time

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Description

Given two integer arrays startTime and endTime and given an integer queryTime.

The ith student started doing their homework at the time startTime[i] and finished it at time endTime[i].

Return _the number of students_ doing their homework at time queryTime. More formally, return the number of students where queryTime lays in the interval [startTime[i], endTime[i]] inclusive.

 

Example 1:

Input: startTime = [1,2,3], endTime = [3,2,7], queryTime = 4
Output: 1
Explanation: We have 3 students where:
The first student started doing homework at time 1 and finished at time 3 and wasn't doing anything at time 4.
The second student started doing homework at time 2 and finished at time 2 and also wasn't doing anything at time 4.
The third student started doing homework at time 3 and finished at time 7 and was the only student doing homework at time 4.

Example 2:

Input: startTime = [4], endTime = [4], queryTime = 4
Output: 1
Explanation: The only student was doing their homework at the queryTime.

 

Constraints:

• startTime.length == endTime.length
• 1 <= startTime.length <= 100
• 1 <= startTime[i] <= endTime[i] <= 1000
• 1 <= queryTime <= 1000

Solutions

Solution 1

class Solution:
  def busyStudent(
    self, startTime: List[int], endTime: List[int], queryTime: int
  ) -> int:
    return sum(a <= queryTime <= b for a, b in zip(startTime, endTime))

class Solution {
  public int busyStudent(int[] startTime, int[] endTime, int queryTime) {
    int ans = 0;
    for (int i = 0; i < startTime.length; ++i) {
      if (startTime[i] <= queryTime && queryTime <= endTime[i]) {
        ++ans;
      }
    }
    return ans;
  }
}

class Solution {
public:
  int busyStudent(vector<int>& startTime, vector<int>& endTime, int queryTime) {
    int ans = 0;
    for (int i = 0; i < startTime.size(); ++i) {
      ans += startTime[i] <= queryTime && queryTime <= endTime[i];
    }
    return ans;
  }
};

func busyStudent(startTime []int, endTime []int, queryTime int) int {
  ans := 0
  for i, a := range startTime {
    b := endTime[i]
    if a <= queryTime && queryTime <= b {
      ans++
    }
  }
  return ans
}

function busyStudent(startTime: number[], endTime: number[], queryTime: number): number {
  const n = startTime.length;
  let res = 0;
  for (let i = 0; i < n; i++) {
    if (startTime[i] <= queryTime && endTime[i] >= queryTime) {
      res++;
    }
  }
  return res;
}

impl Solution {
  pub fn busy_student(start_time: Vec<i32>, end_time: Vec<i32>, query_time: i32) -> i32 {
    let mut res = 0;
    for i in 0..start_time.len() {
      if start_time[i] <= query_time && end_time[i] >= query_time {
        res += 1;
      }
    }
    res
  }
}

int busyStudent(int* startTime, int startTimeSize, int* endTime, int endTimeSize, int queryTime) {
  int res = 0;
  for (int i = 0; i < startTimeSize; i++) {
    if (startTime[i] <= queryTime && endTime[i] >= queryTime) {
      res++;
    }
  }
  return res;
}

Solution 2

class Solution:
  def busyStudent(
    self, startTime: List[int], endTime: List[int], queryTime: int
  ) -> int:
    c = [0] * 1010
    for a, b in zip(startTime, endTime):
      c[a] += 1
      c[b + 1] -= 1
    return sum(c[: queryTime + 1])

class Solution {
  public int busyStudent(int[] startTime, int[] endTime, int queryTime) {
    int[] c = new int[1010];
    for (int i = 0; i < startTime.length; ++i) {
      c[startTime[i]]++;
      c[endTime[i] + 1]--;
    }
    int ans = 0;
    for (int i = 0; i <= queryTime; ++i) {
      ans += c[i];
    }
    return ans;
  }
}

class Solution {
public:
  int busyStudent(vector<int>& startTime, vector<int>& endTime, int queryTime) {
    vector<int> c(1010);
    for (int i = 0; i < startTime.size(); ++i) {
      c[startTime[i]]++;
      c[endTime[i] + 1]--;
    }
    int ans = 0;
    for (int i = 0; i <= queryTime; ++i) {
      ans += c[i];
    }
    return ans;
  }
};

func busyStudent(startTime []int, endTime []int, queryTime int) int {
  c := make([]int, 1010)
  for i, a := range startTime {
    b := endTime[i]
    c[a]++
    c[b+1]--
  }
  ans := 0
  for i := 0; i <= queryTime; i++ {
    ans += c[i]
  }
  return ans
}