Implement SSC algorithm to finish course 2 assignment 1
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@ -0,0 +1,11 @@
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9 3
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9 7
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@ -4,6 +4,7 @@ mod quick_sort;
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mod ssc;
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mod util;
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use std::cmp::min;
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use crate::util::read_to_graph;
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use crate::merge_sort::merge_sort_inversions;
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@ -50,10 +51,12 @@ fn c1a4() {
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#[allow(dead_code)]
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fn c2a1() {
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// I have not checked in the graph file, because it has 70MB.
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// let g = read_to_directed_graph("data/course_2_assignment_1.txt").unwrap();
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let g = read_to_directed_graph("data/course_2_assignment_1_test.txt").unwrap();
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let s = ssc(g.0, g.1);
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println!("{:?}", s);
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let sizes = ssc(g.0, g.1);
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let max_size = min(sizes.len(), 5);
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println!("{:?}", &sizes[0..max_size]);
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}
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fn main() {
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93
src/ssc.rs
93
src/ssc.rs
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@ -1,47 +1,90 @@
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use crate::util::DirectedGraph;
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use std::collections::HashMap;
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fn dfs(mut g: &mut DirectedGraph, node: usize, mut time: &mut usize) -> () {
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fn dfs(g: &mut DirectedGraph, node: usize, time: &mut usize) -> () {
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let mut nodes: Vec<(usize, usize)> = vec![(node, 0)];
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g.explored[node] = true;
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for i in 0..g.nodes[node].len() {
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let j = g.nodes[node][i];
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if !g.explored[j] {
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dfs(&mut g, j, &mut time);
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while nodes.len() > 0 {
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let (mut current_node, mut current_edge) = nodes.pop().unwrap();
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while current_edge < g.nodes[current_node].len() {
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let next_node = g.nodes[current_node][current_edge];
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if !g.explored[next_node] {
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nodes.push((current_node, current_edge + 1));
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current_node = next_node;
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current_edge = 0;
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g.explored[current_node] = true;
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} else {
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current_edge += 1;
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}
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}
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*time += 1;
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g.time[current_node] = *time;
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}
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*time += 1;
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g.time[node] = *time;
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}
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pub fn ssc(g: DirectedGraph, mut g_dash: DirectedGraph) -> u32 {
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let mut time: usize = 0;
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println!("ssc");
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fn second_dfs(g: &mut DirectedGraph, node: usize, leader: usize) -> () {
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let mut nodes: Vec<(usize, usize)> = vec![(node, 0)];
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g.explored[node] = true;
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g.leader[node] = leader;
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while nodes.len() > 0 {
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let (mut current_node, mut current_edge) = nodes.pop().unwrap();
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while current_edge < g.nodes[current_node].len() {
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let next_node = g.nodes[current_node][current_edge];
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if !g.explored[next_node] {
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nodes.push((current_node, current_edge + 1));
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current_node = next_node;
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current_edge = 0;
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g.leader[current_node] = leader;
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g.explored[current_node] = true;
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} else {
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current_edge += 1;
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}
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}
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}
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}
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pub fn ssc(mut g: DirectedGraph, mut g_dash: DirectedGraph) -> Vec<usize> {
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println!("1. start first dfs");
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let mut time: usize = 0;
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for i in (0..g_dash.nodes.len()).rev() {
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if !g_dash.explored[i] {
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dfs(&mut g_dash, i, &mut time);
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}
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}
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println!("finished first dfs");
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println!("2. create time to index mapping");
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let mut time_to_index: Vec<usize> = vec![0; g.nodes.len()];
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for i in 0..g_dash.nodes.len() {
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time_to_index[g_dash.time[i] - 1] = i;
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for node in 0..g_dash.nodes.len() {
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time_to_index[g_dash.time[node] - 1] = node;
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}
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println!("finish time look-up");
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for i in (0..time_to_index.len()).rev() {
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let _node = time_to_index[i];
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// println!("time: {:?} node: {:?}", i, node);
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println!("3. start second dfs");
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for time in (0..time_to_index.len()).rev() {
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let node = time_to_index[time];
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if !g.explored[node] {
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second_dfs(&mut g, node, node);
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}
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}
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println!("finished second dfs");
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for i in 0..g_dash.nodes.len() {
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println!("f({})={}", i + 1, g_dash.time[i]);
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println!("4. print results");
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let mut leader_size: HashMap<usize, usize> = HashMap::new();
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for node in 0..g.nodes.len() {
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let leader = g.leader[node];
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let leader_size = leader_size.entry(leader).or_insert(0);
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*leader_size += 1;
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}
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0
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let mut sizes: Vec<usize> = leader_size.values().cloned().collect();
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sizes.sort();
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sizes.reverse();
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// For debugging the finish time and leader functions.
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// for i in 0..g_dash.nodes.len() {
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// println!("f({})={}", i + 1, g_dash.time[i]);
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// }
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// for i in 0..g.nodes.len() {
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// println!("leader({})={}", i + 1, g.leader[i] + 1);
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// }
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sizes
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}
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34
src/util.rs
34
src/util.rs
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@ -14,6 +14,7 @@ pub struct DirectedGraph {
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pub nodes: Vec<Vec<usize>>,
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pub explored: Vec<bool>,
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pub time: Vec<usize>,
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pub leader: Vec<usize>,
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}
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pub fn read_to_vector(path: &str) -> Result<Vec<i64>, io::Error> {
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@ -59,19 +60,36 @@ pub fn read_to_graph(path: &str) -> Result<Graph, io::Error> {
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Ok(g)
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}
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fn get_node_size(path: &str) -> Result<usize, io::Error> {
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let mut node_size = 0;
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let file = File::open(path)?;
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let br = BufReader::new(file);
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for line in br.lines() {
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let line = line?;
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let mut nodes = line.split_whitespace();
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let node: usize = nodes.next().unwrap().parse().unwrap();
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if node > node_size {
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node_size = node;
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}
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}
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Ok(node_size)
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}
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pub fn read_to_directed_graph(path: &str) -> Result<(DirectedGraph, DirectedGraph), io::Error> {
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const NODES: usize = 9;
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// const NODES: usize = 875714;
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let nodes: usize = get_node_size(path).unwrap();
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let mut g = DirectedGraph {
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nodes: vec![vec![]; NODES],
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explored: vec![false; NODES],
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time: vec![0; NODES],
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nodes: vec![vec![]; nodes],
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explored: vec![false; nodes],
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time: vec![0; nodes],
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leader: vec![0; nodes],
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};
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let mut g_dash = DirectedGraph {
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nodes: vec![vec![]; NODES],
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explored: vec![false; NODES],
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time: vec![0; NODES],
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nodes: vec![vec![]; nodes],
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explored: vec![false; nodes],
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time: vec![0; nodes],
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leader: vec![0; nodes],
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};
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let file = File::open(path)?;
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