dice parser

lib/dice.ts

@@ -0,0 +1,89 @@
+export class Dice {
+  private count!: number;
+  private sides!: number;
+
+  constructor(dice: string) {
+    this.parseDice(dice);
+  }
+
+  private parseDice(dice: string) {
+    const [c, s] = dice.split(/[dD]/);
+    this.count = Number(c);
+    this.sides = Number(s);
+  }
+
+  public roll() {
+    let total = 0;
+    for (let i = 0; i < this.count; i++) {
+      total += this.rollSingle();
+    }
+    return total;
+  }
+
+  private rollSingle() {
+    return Math.ceil(Math.random() * this.sides);
+  }
+
+  public rollAvg() {
+    return this.roll() / this.count;
+  }
+
+  public rollTimes(times: number) {
+    let total = 0;
+    for (let i = 0; i < times; i++) {
+      total += this.roll();
+    }
+    return total;
+  }
+
+  public rollTimesAvg(times: number) {
+    return this.rollTimes(times) / times;
+  }
+
+  public getNormalizedRollDistribution(): Record<number, number> {
+    const distribution: Record<number, number> = this.computeDistribution();
+
+    // Normalize the distribution
+    const totalOutcomes = Math.pow(this.sides, this.count);
+    for (const sum in distribution) {
+      if (distribution.hasOwnProperty(sum)) {
+        distribution[sum] /= totalOutcomes;
+      }
+    }
+
+    return distribution;
+  }
+
+  public getRollDistribution(): Record<number, number> {
+    return this.computeDistribution();
+  }
+
+  private computeDistribution(): Record<number, number> {
+    const distribution: Record<number, number> = {};
+
+    // Helper function to compute the sum distribution for given number of dice
+    const computeSumDistribution = (
+      dice: number,
+      sides: number,
+      currentSum: number,
+      currentDice: number
+    ): void => {
+      if (currentDice === dice) {
+        distribution[currentSum] = (distribution[currentSum] || 0) + 1;
+        return;
+      }
+      for (let i = 1; i <= sides; i++) {
+        computeSumDistribution(dice, sides, currentSum + i, currentDice + 1);
+      }
+    };
+
+    // Compute distribution
+    computeSumDistribution(this.count, this.sides, 0, 0);
+
+    return distribution;
+  }
+  // STATIC
+  static isDice(d: string) {
+    return /\d+[dD]\d+/.test(d);
+  }
+}