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3986. Number of Elapsed Seconds Between Two Times

Description

You are given two valid times startTime and endTime, each represented as a string in the format "HH:MM:SS".

Return the number of seconds that have elapsed from startTime to endTime.

Β 

Example 1:

Input: startTime = "01:00:00", endTime = "01:00:25"

Output: 25

Explanation:

endTime is 25 seconds ahead of startTime.

Example 2:

Input: startTime = "12:34:56", endTime = "13:00:00"

Output: 1504

Explanation:

endTime is 25 minutes and 4 seconds ahead of startTime, which equals 1504 seconds.

Β 

Constraints:

  • startTime.length == 8
  • endTime.length == 8
  • startTime and endTime are valid times in the format "HH:MM:SS"
  • 00 <= HH <= 23
  • 00 <= MM <= 59
  • 00 <= SS <= 59
  • endTime is not earlier than startTime

Solutions

Solution 1: Simulation

Convert each time string into the number of seconds elapsed since \(00\):\(00\):\(00\), i.e. \(HH \times 3600 + MM \times 60 + SS\), then return the difference between the two values.

The time complexity is \(O(1)\), and the space complexity is \(O(1)\).

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class Solution:
    def secondsBetweenTimes(self, startTime: str, endTime: str) -> int:
        def f(s: str) -> int:
            return int(s[:2]) * 3600 + int(s[3:5]) * 60 + int(s[6:])

        return f(endTime) - f(startTime)

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class Solution {
    public int secondsBetweenTimes(String startTime, String endTime) {
        return f(endTime) - f(startTime);
    }

    private int f(String s) {
        return Integer.parseInt(s.substring(0, 2)) * 3600 + Integer.parseInt(s.substring(3, 5)) * 60
            + Integer.parseInt(s.substring(6));
    }
}

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class Solution {
public:
    int secondsBetweenTimes(string startTime, string endTime) {
        return f(endTime) - f(startTime);
    }

private:
    int f(const string& s) {
        return stoi(s.substr(0, 2)) * 3600
            + stoi(s.substr(3, 2)) * 60
            + stoi(s.substr(6));
    }
};

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func secondsBetweenTimes(startTime string, endTime string) int {
    return f(endTime) - f(startTime)
}

func f(s string) int {
    h, _ := strconv.Atoi(s[:2])
    m, _ := strconv.Atoi(s[3:5])
    sec, _ := strconv.Atoi(s[6:])
    return h*3600 + m*60 + sec
}

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function secondsBetweenTimes(startTime: string, endTime: string): number {
    return f(endTime) - f(startTime);
}

function f(s: string): number {
    return parseInt(s.slice(0, 2)) * 3600 + parseInt(s.slice(3, 5)) * 60 + parseInt(s.slice(6));
}

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