Merge pull request wangzheng0822#376 from caitlingao/feat-rust-31-graph

Feat rust 31 graph

Author: wangzheng0822

rust/31_graph/graph_search.rs

@@ -0,0 +1,112 @@
+use std::collections::LinkedList;
+use std::collections::VecDeque;
+
+// 无向图
+#[derive(Debug)]
+struct Graph {
+    v:   i32,
+    linked_vec: Vec<LinkedList<i32>>, // 邻接表
+}
+
+impl Graph {
+    fn new(v: i32) -> Self {
+        Graph {
+            v: v,
+            linked_vec: vec![LinkedList::new(); v as usize],
+        }
+    }
+
+    // 无向图的每条边存两次
+    fn add_edge(&mut self, s: i32, t: i32) {
+        self.linked_vec[s as usize].push_back(t);
+        self.linked_vec[t as usize].push_back(s);
+    }
+
+    fn bfs(&self, s: i32, t: i32) {
+        if s == t { return; }
+
+        let mut prev    = vec![-1; self.v as usize];
+        let mut visited = vec![false; self.v as usize];
+        let mut queue   = VecDeque::new();
+
+        visited[s as usize] = true;
+        queue.push_back(s);
+
+        while !queue.is_empty() {
+            let w = queue.pop_front().unwrap();
+            for item in self.linked_vec[w as usize].iter() {
+                if visited[*item as usize] { continue; }
+                prev[*item as usize] = w;
+                if *item == t {
+                    self.draw(&prev, s, t);
+                    return;
+                }
+                visited[*item as usize] = true;
+                queue.push_back(*item);
+            }
+        }
+    }
+
+    fn dfs(&self, s: i32, t: i32) {
+        let mut found   = false;
+        let mut prev    = vec![-1; self.v as usize];
+        let mut visited = vec![false; self.v as usize];
+
+        self.recur_dfs(s, t, &mut visited, &mut prev, &mut found);
+        self.draw(&prev, s, t);
+    }
+
+    fn recur_dfs(&self,
+                 s:       i32,
+                 t:       i32,
+                 visited: &mut Vec<bool>,
+                 prev:    &mut Vec<i32>,
+                 found:   &mut bool) {
+        if *found == true { return; }
+        visited[s as usize] = true;
+        if s == t {
+            *found = true;
+            return;
+        }
+        for item in self.linked_vec[s as usize].iter() {
+            if visited[*item as usize] { continue; }
+            prev[*item as usize] = s;
+            self.recur_dfs(*item, t, visited, prev, found);
+        }
+    }
+
+    // 递归打印路径
+    fn draw(&self, prev: &Vec<i32>, s: i32, t: i32) {
+        if prev[t as usize] != -1 && s != t {
+            self.draw(prev, s, prev[t as usize]);
+        }
+
+        println!("{} ->", t);
+    }
+}
+
+fn main() {
+    let mut graph = Graph::new(8);
+    graph.add_edge(0, 1);
+    graph.add_edge(0, 3);
+    graph.add_edge(1, 2);
+    graph.add_edge(1, 4);
+    graph.add_edge(2, 5);
+    graph.add_edge(3, 4);
+    graph.add_edge(4, 5);
+    graph.add_edge(4, 6);
+    graph.add_edge(5, 7);
+    graph.add_edge(6, 7);
+
+    // Graph { v: 8, linked_vec: [[1, 3], [0, 2, 4], [1, 5], [0, 4], [1, 3, 5, 6], [2, 4, 7], [4, 7], [5, 6]] }
+    println!("{:?}", graph);
+    graph.bfs(0, 7);
+    println!("bfs=============");
+    graph.bfs(1, 3);
+    println!("bfs=============");
+
+    graph.dfs(0, 7);
+    println!("dfs=============");
+    graph.dfs(1, 3);
+    println!("dfs=============");
+}