Day 21 and 22

scripts/aoc2015/day21/input.txt

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+Hit Points: 109
+Damage: 8
+Armor: 2

scripts/aoc2015/day21/puzzle1.ts

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+/*
+--- Day 21: RPG Simulator 20XX ---
+Little Henry Case got a new video game for Christmas.
+It's an RPG, and he's stuck on a boss.
+He needs to know what equipment to buy at the shop. He hands you the controller.
+
+In this game, the player (you) and the enemy (the boss) take turns attacking.
+The player always goes first.
+Each attack reduces the opponent's hit points by at least 1.
+The first character at or below 0 hit points loses.
+
+Damage dealt by an attacker each turn is equal to the attacker's damage score minus the defender's armor score.
+An attacker always does at least 1 damage.
+So, if the attacker has a damage score of 8, and the defender has an armor score of 3, the defender loses 5 hit points.
+If the defender had an armor score of 300, the defender would still lose 1 hit point.
+
+Your damage score and armor score both start at zero.
+They can be increased by buying items in exchange for gold.
+You start with no items and have as much gold as you need.
+Your total damage or armor is equal to the sum of those stats from all of your items.
+You have 100 hit points.
+
+Here is what the item shop is selling:
+
+Weapons:    Cost  Damage  Armor
+Dagger        8     4       0
+Shortsword   10     5       0
+Warhammer    25     6       0
+Longsword    40     7       0
+Greataxe     74     8       0
+
+Armor:      Cost  Damage  Armor
+Leather      13     0       1
+Chainmail    31     0       2
+Splintmail   53     0       3
+Bandedmail   75     0       4
+Platemail   102     0       5
+
+Rings:      Cost  Damage  Armor
+Damage +1    25     1       0
+Damage +2    50     2       0
+Damage +3   100     3       0
+Defense +1   20     0       1
+Defense +2   40     0       2
+Defense +3   80     0       3
+
+You must buy exactly one weapon; no dual-wielding.
+Armor is optional, but you can't use more than one.
+You can buy 0-2 rings (at most one for each hand).
+You must use any items you buy. The shop only has one of each item, so you can't buy, for example, two rings of Damage +3.
+
+For example, suppose you have 8 hit points, 5 damage, and 5 armor, and that the boss has 12 hit points, 7 damage, and 2 armor:
+
+The player deals 5-2 = 3 damage; the boss goes down to 9 hit points.
+The boss deals 7-5 = 2 damage; the player goes down to 6 hit points.
+The player deals 5-2 = 3 damage; the boss goes down to 6 hit points.
+The boss deals 7-5 = 2 damage; the player goes down to 4 hit points.
+The player deals 5-2 = 3 damage; the boss goes down to 3 hit points.
+The boss deals 7-5 = 2 damage; the player goes down to 2 hit points.
+The player deals 5-2 = 3 damage; the boss goes down to 0 hit points.
+In this scenario, the player wins! (Barely.)
+
+You have 100 hit points. The boss's actual stats are in your puzzle input. What is the least amount of gold you can spend and still win the fight?
+ */
+
+// Algorithm
+
+// create your basic character
+import { Character, modifyCharWithEquip, simulateFight } from "./utils.ts";
+
+const basicPlayer: Character = {
+  hitPoints: 100,
+  damage: 0,
+  defense: 0,
+};
+
+// create boss character (read file)
+const boss: Character = {
+  hitPoints: 109,
+  damage: 8,
+  defense: 2,
+};
+
+// create list of items in shop
+
+// create board with prices
+const board: { character: Character; goldSpent: number }[] = [];
+
+// loop
+// create variations of armor (make sure to safe it's complete price)
+// modify your basic character
+for (const playerWithEquip of modifyCharWithEquip(basicPlayer)) {
+  // simulate fight
+  const playerWins = simulateFight(
+    playerWithEquip.character,
+    Object.assign({}, boss),
+  );
+  // if you win, store price into an board
+  if (playerWins) {
+    board.push(playerWithEquip);
+  }
+}
+console.log("min price ", Math.min(...board.map(({ goldSpent }) => goldSpent)));
+console.log("winner ", board.find(({ goldSpent }) => goldSpent === 111));
+// find min price
+
+// find max price and loose
+
+const looseBoard: { character: Character; goldSpent: number }[] = [];
+
+for (const playerWithEquip of modifyCharWithEquip(basicPlayer)) {
+  // simulate fight
+  const playerWins = simulateFight(
+    playerWithEquip.character,
+    Object.assign({}, boss),
+  );
+  // if you win, store price into an looseBoard
+  if (!playerWins) {
+    looseBoard.push(playerWithEquip);
+  }
+}
+console.log(
+  "Max price ",
+  Math.max(...looseBoard.map(({ goldSpent }) => goldSpent)),
+);
+console.log(
+  "looser with most expensive armor ",
+  looseBoard.find(({ goldSpent }) => goldSpent === 188),
+);

scripts/aoc2015/day21/utils.test.ts

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+import { assert, assertEquals, assertThrows } from "@std/assert";
+import { beforeEach, describe, it } from "@std/testing/bdd";
+import {
+  allArmors,
+  allRings,
+  allWeapons,
+  charAAttacksCharB,
+  Character,
+  equipCharacter,
+  generateRings,
+  simulateFight,
+} from "./utils.ts";
+
+describe("equipCharacter", function () {
+  it("should equip character with some items", function () {
+    const character: Character = {
+      hitPoints: 100,
+      damage: 0,
+      defense: 0,
+    };
+    const armor = allArmors[0];
+    const weapon = allWeapons[0];
+    const ring = allRings[0];
+    assertEquals(
+      equipCharacter(character, {
+        armor,
+        weapon,
+        ringsLeft: ring,
+      }),
+      {
+        character: {
+          ...character,
+          defense: armor.defense + weapon.defense + ring.defense,
+          damage: armor.damage + weapon.damage + ring.damage,
+        },
+        goldSpent: armor.cost + weapon.cost + ring.cost,
+      },
+    );
+  });
+});
+
+describe("generateRings", function () {
+  it("should generate all variations for rings", function () {
+    assertEquals([...generateRings()], [
+      [undefined, undefined],
+      [allRings[0], undefined],
+      [allRings[1], undefined],
+      [allRings[2], undefined],
+      [allRings[3], undefined],
+      [allRings[4], undefined],
+      [allRings[5], undefined],
+      [allRings[0], allRings[1]],
+      [allRings[0], allRings[2]],
+      [allRings[0], allRings[3]],
+      [allRings[0], allRings[4]],
+      [allRings[0], allRings[5]],
+      [allRings[1], allRings[0]],
+      [allRings[1], allRings[2]],
+      [allRings[1], allRings[3]],
+      [allRings[1], allRings[4]],
+      [allRings[1], allRings[5]],
+      [allRings[2], allRings[0]],
+      [allRings[2], allRings[1]],
+      [allRings[2], allRings[3]],
+      [allRings[2], allRings[4]],
+      [allRings[2], allRings[5]],
+      [allRings[3], allRings[0]],
+      [allRings[3], allRings[1]],
+      [allRings[3], allRings[2]],
+      [allRings[3], allRings[4]],
+      [allRings[3], allRings[5]],
+      [allRings[4], allRings[0]],
+      [allRings[4], allRings[1]],
+      [allRings[4], allRings[2]],
+      [allRings[4], allRings[3]],
+      [allRings[4], allRings[5]],
+      [allRings[5], allRings[0]],
+      [allRings[5], allRings[1]],
+      [allRings[5], allRings[2]],
+      [allRings[5], allRings[3]],
+      [allRings[5], allRings[4]],
+    ]);
+  });
+});
+
+describe("charAAttacksCharB", function () {
+  const charA: Character = { hitPoints: 100, damage: 10, defense: 20 };
+  const charB: Character = { hitPoints: 200, damage: 10, defense: 3 };
+
+  it("should execute charA attack on charB", function () {
+    const charAClone = Object.assign({}, charA);
+    const charBClone = Object.assign({}, charB);
+    charAAttacksCharB(charAClone, charBClone);
+    assertEquals(charAClone, charA);
+    assertEquals(charBClone, {
+      ...charB,
+      hitPoints: charB.hitPoints - (charA.damage - charB.defense),
+    });
+  });
+
+  it("should execute charB attack on charA", function () {
+    const charAClone = Object.assign({}, charA);
+    const charBClone = Object.assign({}, charB);
+    charAAttacksCharB(charBClone, charAClone);
+    assertEquals(charBClone, charB);
+    assertEquals(charAClone, {
+      ...charA,
+      hitPoints: charA.hitPoints - 1,
+    });
+  });
+});
+
+describe("simulateFight", function () {
+  it("return true, if player wins", function () {
+    // For example, suppose you have 8 hit points, 5 damage, and 5 armor,
+    // and that the boss has 12 hit points, 7 damage, and 2 armor:
+    assertEquals(
+      simulateFight({
+        hitPoints: 8,
+        damage: 5,
+        defense: 5,
+      }, {
+        hitPoints: 12,
+        damage: 7,
+        defense: 2,
+      }),
+      true,
+    );
+  });
+});