Merge branch 'master' into doc-for-dsu

Author: qryxip

.gitignore

@@ -1,2 +1,3 @@
 /target
 Cargo.lock
+.idea/

README.md

@@ -1,5 +1,10 @@
 # ac-library-rs
 
+[![CI](https://github.com/rust-lang-ja/ac-library-rs/workflows/CI/badge.svg)](https://github.com/rust-lang-ja/ac-library-rs/actions?workflow=CI)
+[![Rust 2018 1.42.0+](https://img.shields.io/badge/rust%202018-1.42.0+-lightgray.svg)](https://www.rust-lang.org)
+![Crates.io](https://img.shields.io/badge/crates.io-not%20yet-inactive)
+![License](https://img.shields.io/badge/license-CC0--1.0-informational)
+
 ac-library-rs is a rust port of AtCoder Library (ACL).
 
 See below for ACL.

src/dsu.rs

@@ -195,11 +195,11 @@ mod tests {
     fn dsu_works() {
         let mut d = Dsu::new(4);
         d.merge(0, 1);
-        assert_eq!(d.same(0, 1), true);
+        assert!(d.same(0, 1));
         d.merge(1, 2);
-        assert_eq!(d.same(0, 2), true);
+        assert!(d.same(0, 2));
         assert_eq!(d.size(0), 3);
-        assert_eq!(d.same(0, 3), false);
+        assert!(!d.same(0, 3));
         assert_eq!(d.groups(), vec![vec![0, 1, 2], vec![3]]);
     }
 }

src/maxflow.rs

@@ -201,7 +201,7 @@ where
             self.graph.g[e_to][e_rev].cap -= d;
             res += d;
             if res == up {
-                break;
+                return res;
             }
         }
         self.iter[v] = self.graph.g[v].len();
@@ -320,4 +320,15 @@ mod test {
 
         assert_eq!(graph.flow(s, t), 2);
     }
+
+    #[test]
+    fn test_dont_repeat_same_phase() {
+        let n = 100_000;
+        let mut graph = MfGraph::new(3);
+        graph.add_edge(0, 1, n);
+        for _ in 0..n {
+            graph.add_edge(1, 2, 1);
+        }
+        assert_eq!(graph.flow(0, 2), n);
+    }
 }

src/mincostflow.rs

@@ -11,7 +11,6 @@ pub struct MinCostFlowEdge<T> {
 pub struct MinCostFlowGraph<T> {
     pos: Vec<(usize, usize)>,
     g: Vec<Vec<_Edge<T>>>,
-    cost_sum: T,
 }
 
 impl<T> MinCostFlowGraph<T>
@@ -22,7 +21,6 @@ where
         Self {
             pos: vec![],
             g: (0..n).map(|_| vec![]).collect(),
-            cost_sum: T::zero(),
         }
     }
 
@@ -56,7 +54,6 @@ where
         assert!(cost >= T::zero());
 
         self.pos.push((from, self.g[from].len()));
-        self.cost_sum += cost;
 
         let rev = self.g[to].len();
         self.g[from].push(_Edge { to, rev, cap, cost });
@@ -131,7 +128,7 @@ where
         pe: &mut [usize],
     ) -> bool {
         let n = self.g.len();
-        let mut dist = vec![self.cost_sum; n];
+        let mut dist = vec![T::max_value(); n];
         let mut vis = vec![false; n];
 
         let mut que = std::collections::BinaryHeap::new();
@@ -209,4 +206,13 @@ mod tests {
         let expected = [(0, 0), (3, 3)];
         assert_eq!(expected[..], *graph.slope(0, 2, i32::max_value()));
     }
+
+    #[test]
+    fn only_one_nonzero_cost_edge() {
+        let mut graph = MinCostFlowGraph::new(3);
+        assert_eq!(0, graph.add_edge(0, 1, 1, 1));
+        assert_eq!(1, graph.add_edge(1, 2, 1, 0));
+        let expected = [(0, 0), (1, 1)];
+        assert_eq!(expected[..], *graph.slope(0, 2, i32::max_value()));
+    }
 }