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539. Minimum Time Difference

Description

Given a list of 24-hour clock time points in "HH:MM" format, return the minimum minutes difference between any two time-points in the list.

 

Example 1:

Input: timePoints = ["23:59","00:00"]
Output: 1

Example 2:

Input: timePoints = ["00:00","23:59","00:00"]
Output: 0

 

Constraints:

• 2 <= timePoints.length <= 2 * 104
• timePoints[i] is in the format "HH:MM".

Solutions

1. Convert all the times into minutes values mins, i.e. 13:14 => 13 * 60 + 14.
2. Sort the mins.
3. Push the time mins[0] + 24 * 60 to deal with min and max diff.
4. For each value in mins[1:], calculate the min diff mins[i] - mins[i - 1].

• Java
• C++
• Python
• Go
• TypeScript
• RenderScript
• Swift

• class Solution {
      public int findMinDifference(List<String> timePoints) {
          if (timePoints.size() > 24 * 60) {
              return 0;
          }
          List<Integer> mins = new ArrayList<>();
          for (String t : timePoints) {
              String[] time = t.split(":");
              mins.add(Integer.parseInt(time[0]) * 60 + Integer.parseInt(time[1]));
          }
          Collections.sort(mins);
          mins.add(mins.get(0) + 24 * 60);
          int res = 24 * 60;
          for (int i = 1; i < mins.size(); ++i) {
              res = Math.min(res, mins.get(i) - mins.get(i - 1));
          }
          return res;
      }
  }
  

• class Solution {
  public:
      int findMinDifference(vector<string>& timePoints) {
          if (timePoints.size() > 24 * 60)
              return 0;
          vector<int> mins;
          for (auto t : timePoints)
              mins.push_back(stoi(t.substr(0, 2)) * 60 + stoi(t.substr(3)));
          sort(mins.begin(), mins.end());
          mins.push_back(mins[0] + 24 * 60);
          int res = 24 * 60;
          for (int i = 1; i < mins.size(); ++i)
              res = min(res, mins[i] - mins[i - 1]);
          return res;
      }
  };
  

• '''
  >>> a = "000"
  >>> int(a)
  0
  
  >>> a = "00011"
  >>> int(a)
  11
  '''
  class Solution:
      def findMinDifference(self, timePoints: List[str]) -> int:
          if len(timePoints) > 24 * 60:
              return 0
          mins = sorted(int(t[:2]) * 60 + int(t[3:]) for t in timePoints)
          mins.append(mins[0] + 24 * 60) # make it a circle, linking 1st and last slot
  
          return min(abs(a - b) for a, b in pairwise(mins))
  
          # below also works, same logic
          # res = mins[-1]
          # for i in range(1, len(mins)):
          #     res = min(res, mins[i] - mins[i - 1])
          # return res
  
  ############
  
  class Solution(object):
    def findMinDifference(self, timePoints):
      """
      :type timePoints: List[str]
      :rtype: int
      """
      ans = 24 * 60
      times = [0] * len(timePoints)
      for i, time in enumerate(timePoints):
        h, m = map(int, time.split(":"))
        times[i] = h * 60 + m
  
      times.sort()
  
      for i in range(len(times) - 1):
        ans = min(ans, abs(times[i] - times[i + 1]))
      return min(ans, 1440 - abs(times[0] - times[-1]))
  
  

• func findMinDifference(timePoints []string) int {
  	if len(timePoints) > 24*60 {
  		return 0
  	}
  	var mins []int
  	for _, t := range timePoints {
  		time := strings.Split(t, ":")
  		h, _ := strconv.Atoi(time[0])
  		m, _ := strconv.Atoi(time[1])
  		mins = append(mins, h*60+m)
  	}
  	sort.Ints(mins)
  	mins = append(mins, mins[0]+24*60)
  	res := 24 * 60
  	for i := 1; i < len(mins); i++ {
  		res = min(res, mins[i]-mins[i-1])
  	}
  	return res
  }
  

• function findMinDifference(timePoints: string[]): number {
      const mins = timePoints
          .map(item => Number(item.slice(0, 2)) * 60 + Number(item.slice(3, 5)))
          .sort((a, b) => a - b);
      const n = mins.length;
      let res = Infinity;
      for (let i = 0; i < n - 1; i++) {
          res = Math.min(res, mins[i + 1] - mins[i]);
      }
  
      const first = mins[0] + 24 * 60;
      const last = mins[n - 1];
      res = Math.min(res, first - last);
  
      return res;
  }
  
  

• impl Solution {
      pub fn find_min_difference(time_points: Vec<String>) -> i32 {
          if time_points.len() > 1440 {
              return 0;
          }
  
          let n = time_points.len();
          let mut nums: Vec<i32> = Vec::with_capacity(n + 1);
  
          for time in time_points.iter() {
              let parts: Vec<i32> = time.split(':').map(|s| s.parse().unwrap()).collect();
              let minutes = parts[0] * 60 + parts[1];
              nums.push(minutes);
          }
  
          nums.sort();
          nums.push(nums[0] + 1440);
  
          let mut ans = i32::MAX;
          for i in 1..=n {
              ans = ans.min(nums[i] - nums[i - 1]);
          }
  
          ans
      }
  }
  
  

• class Solution {
      func findMinDifference(_ timePoints: [String]) -> Int {
          if timePoints.count > 1440 {
              return 0
          }
  
          var nums = [Int]()
  
          for t in timePoints {
              let time = t.split(separator: ":").map { Int($0)! }
              nums.append(time[0] * 60 + time[1])
          }
  
          nums.sort()
          nums.append(nums[0] + 1440)
  
          var ans = Int.max
          for i in 1..<nums.count {
              ans = min(ans, nums[i] - nums[i - 1])
          }
  
          return ans
      }
  }
  

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