Bishop and Pawn

Definition

The “Bishop and Pawn” algorithm is a classic programming exercise (popular on platforms like CodeSignal or GeeksforGeeks) designed to test your understanding of coordinate geometry on a 2D grid.It boils down to one simple question: “Can a Bishop at $(x_1, y_1)$ capture a Pawn at $(x_2, y_2)$ in exactly one move?”

const bishopAndPawn = function (bishop, pawn) {
  const board = {
    a:1,b:2,c:3,d:4,e:5,f:6,g:7,h:8
  };

  const bishopX = board[bishop[0]];
  const bishopY = parseInt(bishop[1]);

  const pawnX = board[pawn[0]];
  const pawnY = parseInt(pawn[1]);

  if (
    bishopX + bishopY === pawnX + pawnY ||
    bishopX - bishopY === pawnX - pawnY
  ) {
    return true;
  }

  return false;
};

How It Works

1. Summary

♟️ How It Works

1. Board Mapping

const board = { “a”:1, “b”:2, “c”:3, “d”:4, “e”:5, “f”:6, “g”:7, “h”:8 };

• Converts chess columns (a–h) into numeric values (1–8).

2. Extract Coordinates

Bishop

const bishopX = board[bishop[0]]; const bishopY = parseInt(bishop[1]);

Pawn

const pawnX = board[pawn[0]]; const pawnY = parseInt[pawn[1]];

• Splits positions like “c1” into:

  • X (column)
  • Y (row)

3. Capture Logic

#### if ( bishopX + bishopY === pawnX + pawnY || bishopX + pawnY === pawnX + bishopY )

• A bishop moves diagonally.

• Two squares are on the same diagonal if:

  • Their sum is equal, OR
  • Their difference is equal (represented here using rearranged sums)

4. Return Result

return true; // if capture possible return