// Swap two elements in an array
function swap<T>(arr: T[], i: number, j: number): void {
[arr[i], arr[j]] = [arr[j], arr[i]];
}
// Print array of chars
function printArray(arr: string[]): void {
console.log(arr.join(" "));
}
// Recursive function to generate permutations
function permute(arr: string[], l: number, r: number): void {
if (l === r) {
printArray(arr);
return;
}
for (let i = l; i <= r; i++) {
swap(arr, l, i);
permute(arr, l + 1, r);
swap(arr, l, i); // backtrack
}
}
// Generate all combinations using bitmask
function generateCombinations(arr: string[]): void {
const size = arr.length;
for (let mask = 1; mask < (1 << size); mask++) {
const combo: string[] = [];
for (let i = 0; i < size; i++) {
if (mask & (1 << i)) {
combo.push(arr[i]);
}
}
console.log(combo.join(" "));
}
}
function main(): void {
const input = ["a", "b", "c"];
const size = input.length;
console.log("All permutations:");
permute([...input], 0, size - 1);
console.log("\nAll combinations:");
generateCombinations(input);
}
main();
/*
run:
"All permutations:"
"a b c"
"a c b"
"b a c"
"b c a"
"c b a"
"c a b"
"
All combinations:"
"a"
"b"
"a b"
"c"
"a c"
"b c"
"a b c"
*/
