Lesson 1: FrogJmp (Frog Jmp)

This one is quite easy.
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Complexity:

• expected worst-case time complexity is O(1);
• expected worst-case space complexity is O(1).

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int solution(int X, int Y, int D) {

    int distance = Y - X;

    return distance % D == 0 ? distance / D : distance / D + 1;

}