52 lines
864 B
Rust
52 lines
864 B
Rust
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// compile-flags: -Zinline-mir
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use std::fmt::Display;
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fn main() {
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permutations(&['a', 'b', 'c']);
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}
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#[inline(always)]
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fn permutations<T: Copy + Display>(xs: &[T]) {
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let mut ys = xs.to_owned();
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permutate(&mut ys, 0);
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}
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fn permutate<T: Copy + Display>(xs: &mut [T], k: usize) {
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let n = length(xs);
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if k == n {
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display(xs);
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} else if k < n {
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for i in k..n {
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swap(xs, i, k);
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permutate(xs, k + 1);
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swap(xs, i, k);
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}
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} else {
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error();
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}
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}
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fn length<T>(xs: &[T]) -> usize {
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xs.len()
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}
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#[inline]
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fn swap<T: Copy>(xs: &mut [T], i: usize, j: usize) {
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let t = xs[i];
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xs[i] = xs[j];
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xs[j] = t;
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}
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fn display<T: Display>(xs: &[T]) {
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for x in xs {
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print!("{}", x);
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}
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println!();
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}
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#[inline(always)]
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fn error() {
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panic!("error");
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}
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