Vincent Bourdon
93 lines
2.1 KiB
Rust
93 lines
2.1 KiB
Rust
use spinoza::utils::padded_bin;
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fn print_pairs() {
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let timer = std::time::Instant::now();
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let n = 6;
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let p2n = 1 << n;
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let t = 0;
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let p2t = 1 << t;
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let c = 3;
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let p2c = 1 << (c + 1);
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let p2m = 1 << (c - t - 1);
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for i in 0..p2m {
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for j in (2 * i + 2 * p2m + 1) * p2t..(2 * i + 2 * p2m + 2) * p2t {
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// println!("{} = {}", j, padded_bin(j, n));
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for k in (j..j + p2n).step_by(p2c) {
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println!("{} = {}", k, padded_bin(k, n));
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}
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}
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}
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println!("time elapsed: {} us ... ", timer.elapsed().as_micros());
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}
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fn print_target_pairs() {
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let n = 3;
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let target = 1;
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let dist = 1 << target;
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// 2 for loops
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println!("for loops");
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for i in 0..1 << (n - 1 - target) {
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for j in 2 * i * dist..(2 * i + 1) * dist {
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println!(
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"{} = {} -> {} = {}",
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j,
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padded_bin(j, n),
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dist + j,
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padded_bin(dist + j, n)
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)
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}
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}
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// divmod
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println!("\ndivmod");
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for i in 0..1 << (n - 1) {
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// let (p, s) = (i / dist, i % dist);
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// i = dist*p + s
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let j = i + ((i >> target) << target); //i + (p << target); // i + dist*p; // 2 * dist * p + s;
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println!(
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"{} = {} -> {} = {}",
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j,
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padded_bin(j, n),
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dist + j, // i + ((1 + (i >> target)) << target),
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padded_bin(dist + j, n)
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)
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}
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// bit manipulation
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println!("\nbit manipulation");
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let neg_dist = !0 << target;
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for i in 0..1 << (n - 1) {
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let j = i + (i & neg_dist);
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println!(
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"{} = {} -> {} = {}",
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j,
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padded_bin(j, n),
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dist + j,
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padded_bin(dist + j, n)
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)
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}
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for target in 0..n {
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for i in 0..1 << (n - 1) {
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assert_eq!(
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(i >> target) << target,
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i & !0 << target,
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"different for {}",
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i
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);
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}
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}
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}
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fn main() {
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print_target_pairs();
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print_pairs();
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}
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