Codility: Frog Jump

Count minimal number of jumps from position X to Y.

Question

A small frog wants to get to the other side of the road. The frog is currently located at position X and wants to get to a position greater than or equal to Y. The small frog always jumps a fixed distance, D.

Count the minimal number of jumps that the small frog must perform to reach its target.

Write a function:

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

that, given three integers X, Y and D, returns the minimal number of jumps from position X to a position equal to or greater than Y.

For example, given:

  X = 10
  Y = 85
  D = 30

the function should return 3, because the frog will be positioned as follows:

  • after the first jump, at position 10 + 30 = 40
  • after the second jump, at position 10 + 30 + 30 = 70
  • after the third jump, at position 10 + 30 + 30 + 30 = 100

Assume that:

  • X, Y and D are integers within the range [1..1,000,000,000];
  • X ≤ Y.

Complexity:

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

Solution

-(int)frogJumpStart:(int)x destination:(int)y distance:(int)d {
    
    int res = (y-x)/d;
    if((y-x)%d != 0){
        res++;
    }
    NSLog(@"%d", res);
    return res;
}
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