Try several operator counts

board-shared/src/ai.rs

@@ -44,16 +44,18 @@ 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) {
-                    merge_expression(&digits, &operators, equals_idx, &mut trial);
+                    for operators in operators.iter().permutations(nb_operators) {
-                    if let Ok(tokens) = lexer(&trial) {
+                        merge_expression(&digits, &operators, equals_idx, &mut trial);
-                        if let Ok(expressions) = parse(&tokens) {
+                        if let Ok(tokens) = lexer(&trial) {
-                            if are_valid_expressions(&expressions) {
+                            if let Ok(expressions) = parse(&tokens) {
-                                combinations.push(trial.clone());
+                                if are_valid_expressions(&expressions) {
+                                    combinations.push(trial.clone());
+                                }
                             }
                         }
+                        trial.clear();
                     }
-                    trial.clear();
                 }
             }
         }