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

Write an efficient algorithm for the following assumptions:

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

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(X, Y, D) {
    // write your code in JavaScript (Node.js 8.9.4)
    let result = Math.floor((Y-X)/D);
    return (Y-X)%D > 0 ? result+1 : result;
}

Math.floor() 함수

- 주어진 숫자와 같거나 작은 정수 중에서 가장 큰수 반환

parseInt사용시 뒤에 쉼표 후 진수 표기 필수