Rock Paper Scissors!

Rock Paper Scissors!Codewars

Approach

find pattern

• rock < paper < scissors < rock

  • when p1(player 1) rock

    • paper - p1 lose

    • scissors - p1 win

  • when p1 paper

    • scissors - p1 lose

    • rock - p1 win

  • when p1 rock

    • paper - p1 lose

    • scissors - p1 win

in this infinite pattern

• when meet n+1 element lose

• when meet n-1 element win

solve the problem

1. prepare array ['rock', 'paper', scissors'] (pattern)

2. find index input x's index in pattern array and

   find index input y's index in pattern array

3. if (x index plus 1) % 3 is same with y index = p2 win

4. if (x index plus 2) % 3 is same with y index = p1 win

5. if x,y index same = draw

Solution

JavaScript

const rps = (p1, p2) => {
  const pattern = ['rock', 'paper', 'scissors'];
  const p1Index = pattern.findIndex((v) => v === p1);
  const p2Index = pattern.findIndex((v) => v === p2);
  
  if ((p1Index + 1) % 3 === p2Index) {
    return 'Player 2 won!';
  }
  if ((p1Index + 2) % 3 === p2Index) {
    return 'Player 1 won!';
  }
  
  return 'Draw!';
};