lr-core/utils/hashNumberPair.js

Line Rider core library

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.hashUIntPair = hashUIntPair;
exports.unhashUIntPair = unhashUIntPair;
exports.hashIntPair = hashIntPair;
exports.unhashIntPair = unhashIntPair;
// http://stackoverflow.com/a/13871379
function hashUIntPair(a, b) {
  return a >= b ? a * a + a + b : b * b + a;
}

function unhashUIntPair(n) {
  let x = Math.sqrt(n) | 0; // x = a < b ? b : a
  let r = n - x * x; //        r = a < b ? a : a+b
  if (r < x) {
    // r = a, x = b, a < b
    return [r, x];
  } else {
    // r = a+b, x = a
    return [x, r - x];
  }
}

function hashIntPair(a, b) {
  let A = a >= 0 ? 2 * a : -2 * a - 1;
  let B = b >= 0 ? 2 * b : -2 * b - 1;
  let C = A >= B ? A * A + A + B : B * B + A;
  return C & 1 ? -(C - 1) / 2 - 1 : C / 2;
}

function unhashIntPair(n) {
  let C = n >= 0 ? n * 2 : -(n + 1) * 2 + 1;
  let [A, B] = unhashUIntPair(C);
  let a = A & 1 ? -(A + 1) / 2 : A / 2;
  let b = B & 1 ? -(B + 1) / 2 : B / 2;
  return [a, b];
}