Update PrimaryProblem.java

src/PrimaryProblem.java

@@ -1,44 +1,29 @@
+import java.util.List;
 import java.util.Random;
 
+/**
+ * 生成小学题目
+ */
 public class PrimaryProblem implements ProblemsGenerator {
   private static final Random RANDOM = new Random();
-  private static final String[] OPERATORS = {"+", "-", "*", "/"};
+  private final BracketManager bracketManager = new BracketManager();
+  private final ExpressionBuilder expressionBuilder = new ExpressionBuilder();
   
   @Override
   public String generate() {
-    int count = RANDOM.nextInt(4) + 2;
-    StringBuilder sb = new StringBuilder();
+    String expression;
+    do {
+      int numCount = 2 + RANDOM.nextInt(4);
+      expression = expressionBuilder.generateBasicExpression(numCount);
 
-    boolean addParentheses = count >= 3 && RANDOM.nextDouble() < 0.5;
-    if (addParentheses) {
-      int parenCount = RANDOM.nextInt(count - 2) + 2;
-      int startPos = RANDOM.nextInt(count - parenCount + 1);
-      
-      for (int i = 0; i < count; i++) {
-        if (i == startPos) {
-          sb.append("( ");
+      List<Integer> numPositions = expressionBuilder.getNumberPositions(expression);
+      int pairs = bracketManager.decideParenthesesPairs(numCount);
+      if (pairs > 0) {
+        expression = bracketManager.addParentheses(expression, pairs, numPositions);
       }
       
-        int num = RANDOM.nextInt(100) + 1;
-        sb.append(num);
-        
-        if (i == startPos + parenCount - 1) {
-          sb.append(" )");
-        }
+    } while (expressionBuilder.hasDivideByZero(expression));
     
-        if (i < count - 1) {
-          sb.append(" ").append(OPERATORS[RANDOM.nextInt(OPERATORS.length)]).append(" ");
-        }
-      }
-    } else {
-      for (int i = 0; i < count; i++) {
-        int num = RANDOM.nextInt(100) + 1;
-        sb.append(num);
-        if (i < count - 1) {
-          sb.append(" ").append(OPERATORS[RANDOM.nextInt(OPERATORS.length)]).append(" ");
-        }
-      }
-    }
-    return sb.toString();
+    return expression;
   }
 }