Solutions for challenge #109

1 files changed, 29 insertions, 0 deletions

diff --git a/challenge-109/roger-bell-west/rust/ch-2.rs b/challenge-109/roger-bell-west/rust/ch-2.rs
new file mode 100644
index 0000000000..a7f46258c0
--- /dev/null
+++ b/challenge-109/roger-bell-west/rust/ch-2.rs
@@ -0,0 +1,29 @@
+use permutohedron::LexicalPermutation;
+
+#[test]
+fn test_ex1() {
+    let q=foursquare((1..=7).collect::<Vec<i32>>());
+    assert_eq!(q[0],q[2]+q[3]);
+    assert_eq!(q[1]+q[2],q[4]+q[5]);
+    assert_eq!(q[3]+q[4],q[6]);
+}
+
+fn foursquare(src: Vec<i32>) -> Vec<i32> {
+    let mut t=src;
+    let mut sol: Vec<i32>=vec![];
+    t.sort();
+    loop {
+        let b=t[1]+t[2]+t[3];
+        if t[0]+t[1]==b {
+            let c=t[3]+t[4]+t[5];
+            if b==c && c == t[5]+t[6] {
+                sol=t;
+                break;
+            }
+        }
+        if !t.next_permutation() {
+            break;
+        }
+    }
+    return sol;
+}