105 lines
3.9 KiB
Rust
105 lines
3.9 KiB
Rust
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#![cfg(feature = "ndarray")]
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use ndarray::{s, Array2};
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use rand::SeedableRng;
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use rand_chacha::ChaCha20Rng;
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use smawk::{brute_force, online_column_minima, recursive};
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mod random_monge;
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use random_monge::random_monge_matrix;
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/// Check that the brute force, recursive, and SMAWK functions
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/// give identical results on a large number of randomly generated
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/// Monge matrices.
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#[test]
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fn column_minima_agree() {
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let sizes = vec![1, 2, 3, 4, 5, 10, 15, 20, 30];
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let mut rng = ChaCha20Rng::seed_from_u64(0);
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for _ in 0..4 {
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for m in sizes.clone().iter() {
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for n in sizes.clone().iter() {
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let matrix: Array2<i32> = random_monge_matrix(*m, *n, &mut rng);
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// Compute and test row minima.
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let brute_force = brute_force::row_minima(&matrix);
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let recursive = recursive::row_minima(&matrix);
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let smawk = smawk::row_minima(&matrix);
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assert_eq!(
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brute_force, recursive,
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"recursive and brute force differs on:\n{:?}",
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matrix
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);
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assert_eq!(
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brute_force, smawk,
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"SMAWK and brute force differs on:\n{:?}",
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matrix
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);
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// Do the same for the column minima.
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let brute_force = brute_force::column_minima(&matrix);
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let recursive = recursive::column_minima(&matrix);
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let smawk = smawk::column_minima(&matrix);
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assert_eq!(
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brute_force, recursive,
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"recursive and brute force differs on:\n{:?}",
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matrix
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);
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assert_eq!(
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brute_force, smawk,
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"SMAWK and brute force differs on:\n{:?}",
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matrix
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);
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}
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}
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}
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}
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/// Check that the brute force and online SMAWK functions give
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/// identical results on a large number of randomly generated
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/// Monge matrices.
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#[test]
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fn online_agree() {
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let sizes = vec![1, 2, 3, 4, 5, 10, 15, 20, 30, 50];
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let mut rng = ChaCha20Rng::seed_from_u64(0);
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for _ in 0..5 {
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for &size in &sizes {
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// Random totally monotone square matrix of the
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// desired size.
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let mut matrix: Array2<i32> = random_monge_matrix(size, size, &mut rng);
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// Adjust matrix so the column minima are above the
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// diagonal. The brute_force::column_minima will still
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// work just fine on such a mangled Monge matrix.
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let max = *matrix.iter().max().unwrap_or(&0);
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for idx in 0..(size as isize) {
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// Using the maximum value of the matrix instead
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// of i32::max_value() makes for prettier matrices
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// in case we want to print them.
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matrix.slice_mut(s![idx..idx + 1, ..idx + 1]).fill(max);
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}
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// The online algorithm always returns the initial
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// value for the left-most column -- without
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// inspecting the column at all. So we fill the
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// left-most column with this value to have the brute
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// force algorithm do the same.
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let initial = 42;
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matrix.slice_mut(s![0.., ..1]).fill(initial);
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// Brute-force computation of column minima, returned
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// in the same form as online_column_minima.
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let brute_force = brute_force::column_minima(&matrix)
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.iter()
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.enumerate()
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.map(|(j, &i)| (i, matrix[[i, j]]))
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.collect::<Vec<_>>();
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let online = online_column_minima(initial, size, |_, i, j| matrix[[i, j]]);
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assert_eq!(
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brute_force, online,
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"brute force and online differ on:\n{:3?}",
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matrix
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);
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}
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}
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}
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