null if the sums of the two vec are not equal

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "subset_sum"
-version = "0.8.3"
+version = "0.8.4"
 edition = "2018"
 authors = ["Tomohiro Endo <europeanplaice@gmail.com>"]
 description = "Solves subset sum problem and returns a set of decomposed integers. It also can match corresponding numbers from two vectors and be used for Account reconciliation." 

src/dp_module.rs

@@ -364,6 +364,10 @@ pub mod dp {
         n_key: usize,
         key_orig: &mut Vec<i32>,
     ) {
+        if key.iter().sum::<i32>() != targets.iter().sum() {
+            return;
+        }
+
         if key.len() == 0 && targets.len() == 0 {
             answer.push(group.clone());
             return;
@@ -527,6 +531,10 @@ pub mod dp {
                 ),
             ]
         );
+
+        let answer = sequence_matcher_m2m(&mut vec![1, 2, 3, 4], &mut vec![1, 5], 10);
+
+        assert_eq!(answer.len(), 0);
     }
 }