sorts: Fix position error in selection sort

XuShaohua · Nov 15, 2023 · beedec6 · beedec6
1 parent 5f0c3d8
commit beedec6
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Showing 3 changed files with 33 additions and 8 deletions.
diff --git a/robert/src/bin/selection_sort.rs b/robert/src/bin/selection_sort.rs
@@ -2,12 +2,18 @@
 // Use of this source is governed by General Public License that can be found
 // in the LICENSE file.
 
-use robert::util::{read_ints, show};
+use robert::util::{is_sorted, read_ints, show};
 use sorts::selection_sort;
 
 fn main() {
     let mut list = read_ints();
     selection_sort(&mut list);
+    assert!(is_sorted(&list));
     println!("RESULT:");
-    show(&list);
+    if list.len() < 128 {
+        show(&list);
+    } else {
+        show(&list[..128]);
+        println!("...\n...");
+    }
 }
diff --git a/robert/src/util.rs b/robert/src/util.rs
@@ -2,6 +2,7 @@
 // Use of this source is governed by General Public License that can be found
 // in the LICENSE file.
 
+use std::fmt;
 use std::io::{self, BufRead, BufReader};
 
 pub fn exch<T>(list: &mut Vec<T>, i: usize, j: usize)
@@ -15,10 +16,15 @@ where
 
 pub fn is_sorted<T>(list: &[T]) -> bool
 where
-    T: PartialOrd,
+    T: PartialOrd + fmt::Debug,
 {
     for i in 0..(list.len() - 1) {
         if list[i] > list[i + 1] {
+            println!(
+                "Order error at: {i}, values: ({:?}, {:?})",
+                list[i],
+                list[i + 1]
+            );
             return false;
         }
     }
@@ -27,7 +33,7 @@ where
 
 pub fn show<T>(vec: &[T])
 where
-    T: std::fmt::Display,
+    T: fmt::Display,
 {
     for s in vec {
         print!("{} ", s);

diff --git a/sorts/src/selection_sort.rs b/sorts/src/selection_sort.rs
@@ -28,12 +28,12 @@ pub fn selection_sort(list: &mut [i32]) {
     for i in 0..(len - 1) {
         let mut min_index = i;
         for j in (i + 1)..len {
-            if list[min_index] > list[j] {
+            if list[j] < list[min_index] {
                 min_index = j;
             }
-            if i != min_index {
-                list.swap(i, min_index);
-            }
+        }
+        if i != min_index {
+            list.swap(i, min_index);
         }
     }
 }
@@ -51,5 +51,18 @@ mod tests {
         let mut list = [-2, -5, -45];
         selection_sort(&mut list);
         assert_eq!(list, [-45, -5, -2]);
+
+        let mut list = [
+            -998166, -996360, -995703, -995238, -995066, -994740, -992987, -983833, -987905,
+            -980069, -977640,
+        ];
+        selection_sort(&mut list);
+        assert_eq!(
+            list,
+            [
+                -998166, -996360, -995703, -995238, -995066, -994740, -992987, -987905, -983833,
+                -980069, -977640,
+            ]
+        );
     }
 }