019f8fd211
git-subtree-dir: users/wpcarro git-subtree-mainline:464bbcb15cgit-subtree-split:24f5a642afChange-Id: I6105b3762b79126b3488359c95978cadb3efa789
102 lines
2.4 KiB
TypeScript
102 lines
2.4 KiB
TypeScript
// The denomination of a coin.
|
|
type Coin = number;
|
|
|
|
// The amount of change remaining.
|
|
type Amount = number;
|
|
|
|
// Mapping of Coin -> Int
|
|
type CoinBag = Map<Coin, number>;
|
|
|
|
function createCoinBag(coins: Coin[]): CoinBag {
|
|
const result = new Map();
|
|
|
|
for (const coin of coins) {
|
|
result.set(coin, 0);
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
// This algorithm should work conceptual, but it does not actually
|
|
// work. JavaScript uses reference equality when constructing a Set<Map<A,B>>,
|
|
// so my result.size returns a higher number than I expect because it contains
|
|
// many duplicate entries.
|
|
//
|
|
// Conceptually, I'm not sure this solution is optimal either -- even after I
|
|
// can dedupe the entries in `result`.
|
|
function changePossibilities(amt: Amount, coins: Coin[]): number {
|
|
if (amt === 0) {
|
|
return 1;
|
|
}
|
|
const result: Set<CoinBag> = new Set();
|
|
|
|
const q: [Coin, Amount, CoinBag][] = [];
|
|
|
|
for (const coin of coins) {
|
|
const bag = createCoinBag(coins);
|
|
bag.set(coin, 1);
|
|
q.push([coin, amt - coin, bag]);
|
|
}
|
|
|
|
while (q.length > 0) {
|
|
const [coin, amt, bag] = q.shift();
|
|
|
|
console.log([coin, amt, bag]);
|
|
|
|
if (amt === 0) {
|
|
result.add(bag);
|
|
} else if (amt < 0) {
|
|
continue;
|
|
} else {
|
|
for (const c of coins) {
|
|
const bagCopy = new Map(bag);
|
|
const value = bagCopy.get(c);
|
|
bagCopy.set(c, value + 1);
|
|
q.push([c, amt - c, bagCopy]);
|
|
}
|
|
}
|
|
}
|
|
console.log(result);
|
|
return result.size;
|
|
}
|
|
|
|
// Tests
|
|
let desc = "sample input";
|
|
let actual = changePossibilities(4, [1, 2, 3]);
|
|
let expected = 4;
|
|
assertEqual(actual, expected, desc);
|
|
|
|
desc = "one way to make zero cents";
|
|
actual = changePossibilities(0, [1, 2]);
|
|
expected = 1;
|
|
assertEqual(actual, expected, desc);
|
|
|
|
desc = "no ways if no coins";
|
|
actual = changePossibilities(1, []);
|
|
expected = 0;
|
|
assertEqual(actual, expected, desc);
|
|
|
|
desc = "big coin value";
|
|
actual = changePossibilities(5, [25, 50]);
|
|
expected = 0;
|
|
assertEqual(actual, expected, desc);
|
|
|
|
desc = "big target amount";
|
|
actual = changePossibilities(50, [5, 10]);
|
|
expected = 6;
|
|
assertEqual(actual, expected, desc);
|
|
|
|
// I think InterviewCake designed this assertion to be computationally
|
|
// expensive.
|
|
desc = "change for one dollar";
|
|
actual = changePossibilities(100, [1, 5, 10, 25, 50]);
|
|
expected = 292;
|
|
assertEqual(actual, expected, desc);
|
|
|
|
function assertEqual(a, b, desc) {
|
|
if (a === b) {
|
|
console.log(`${desc} ... PASS`);
|
|
} else {
|
|
console.log(`${desc} ... FAIL: ${a} != ${b}`);
|
|
}
|
|
}
|