Try several operator counts

board-shared/src/ai.rs

@@ -44,7 +44,8 @@ pub fn generate_valid_combinations(hand: &Hand) -> Vec<Vec<Tile>> {
             // Then try to place the equals sign at each possible position
             // Since equality is commutative, we only need to try half of the positions
             for equals_idx in 0..(nb_digits / 2) {
-                for operators in operators.iter().permutations(nb_digits - 2) {
+                for nb_operators in 0..=(nb_digits - 2) {
+                    for operators in operators.iter().permutations(nb_operators) {
                         merge_expression(&digits, &operators, equals_idx, &mut trial);
                         if let Ok(tokens) = lexer(&trial) {
                             if let Ok(expressions) = parse(&tokens) {
@@ -58,6 +59,7 @@ pub fn generate_valid_combinations(hand: &Hand) -> Vec<Vec<Tile>> {
                 }
             }
         }
+    }
     combinations
 }