Human-readable solution for the problem at the end of https://codility.com/media/train/12-BinarySearch.pdf

BoardsCoveringRooftopHoles.js

function boardsBinarySearch(A, numBoards) {
  var n = A.length;
  var minBoardSize = 1;
  var maxBoardSize = n;
  var result = -1;
  while (minBoardSize <= maxBoardSize) {
    var tentativeBoardSize = Math.floor((minBoardSize + maxBoardSize) / 2);
    if (neededBoards(A, tentativeBoardSize) <= numBoards) {
      result = tentativeBoardSize;
      maxBoardSize = tentativeBoardSize - 1;
    } else {
      minBoardSize = tentativeBoardSize + 1;
    }
  }
  return result;
}

function neededBoards(A, boardSize) {
  var beginLastBoard = -1;
  var numBoards = 0;
  for (var i = 0; i < A.length; i++) {
    if (!A[i]) continue; // solid wood
    if (beginLastBoard > 0 && (beginLastBoard + boardSize -1) >= i) continue; // there's a board, and it's still covering the hole
    numBoards++;
    beginLastBoard = i;
  }
  return numBoards;
}