3-2.FrogJmp

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:

function solution(X, Y, 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).

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// Correctness 100%
// Performance 100%
// Task Score 100%
function solution(X, Y, D) {
    // write your code in JavaScript (Node.js 6.4.0)
    
    return (Y - X) % D === 0 ? (Y - X) / D : Math.floor((Y - X) / D) + 1;
}