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Generate Lotto 6 and Lotto 7 Numbers in TypeScript

A TypeScript implementation that generates Lotto 6 and Lotto 7 numbers with the Mersenne Twister. A practical example of a pseudorandom number generator.

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I built a small Lotto 6 and Lotto 7 number generator just for fun.

Implementation

function generateLottoNumbers(lot: 6 | 7): number[] {
if (![6, 7].includes(lot)) {
throw new Error('引数は6または7である必要があります');
}
const { random } = createMersenneTwister();
const min = 1, max = lot === 6 ? 43 : 37
const numbers = new Set<number>();
while (numbers.size < lot) {
numbers.add(Math.floor(random() * (max - min + 1)) + min);
}
return [...numbers];
}

Mersenne Twister implementation

export function createMersenneTwister(seed: number = new Date().getTime()) {
let index = 624;
const MT = new Array(624);
MT[0] = seed;
for (let i = 1; i < 624; i++) {
MT[i] = (1812433253 * (MT[i - 1] ^ (MT[i - 1] >>> 30)) + i) >>> 0;
}
function generateNumbers() {
for (let i = 0; i < 624; i++) {
const y = (MT[i] & 0x80000000) + (MT[(i + 1) % 624] & 0x7fffffff);
MT[i] = MT[(i + 397) % 624] ^ (y >>> 1);
if (y % 2 !== 0) {
MT[i] ^= 2567483615;
}
}
}
function random() {
if (index >= 624) {
generateNumbers();
index = 0;
}
let y = MT[index++];
y ^= (y >>> 11);
y ^= (y << 7) & 2636928640;
y ^= (y << 15) & 4022730752;
y ^= (y >>> 18);
return (y >>> 0) / 4294967296;
}
return { random };
}

Points

  • Set: generates unique numbers without duplicates
  • Mersenne Twister: a high-quality pseudorandom number generator
  • Range: Lotto 6 uses 1-43, Lotto 7 uses 1-37

Summary

With the Mersenne Twister, you can generate better random numbers than Math.random().

Whether they actually win a lottery is a different story, but as practice for implementing a pseudorandom algorithm, it is a decent example.