一年级数学上 20以内加减法算式生成(3个运算数)

输出样例

• 7  +  8  -  4 = (   )    |     5  -  3  +  7 = (   )

• 18  -  5  - 11 = (   )    |    16  - 12  +  2 = (   )

• 12  - 10  + (   ) = 13    |     4  + (   )  + 11 = 17

• 3  + 11  - (   ) = 10    |    10  -  8  + (   ) = 18

• 2  + 16  - (   ) = 13    |     9  +  3  - (   ) =  6

• (   )  - 14  +  2 =  3    |    15  + (   )  +  1 = 19

• 5  +  6  - (   ) =  4    |   (   )  -  4  -  2 =  7

代码

package com.erduo.duolaiapp.data.util;
import java.util.*;


/**
 * 20以内加减法算式生成(3个运算数)
 * @author erDuo
 * @date 2024/01/25 15:05
 */
public class MathAddSubPractice {

    // 运算数 统计
    public static HashMap<Object, Integer> OPERATOR_COUNT = new HashMap<Object, Integer>() {
        {
            put(1, 0);
            put(2, 0);
            put(3, 0);
            put(4, 0);
            put(5, 0);
            put(6, 0);
            put(7, 0);
            put(8, 0);
            put(9, 0);
            put("+", 0);
            put("-", 0);
        }
    };

    // 算式输出
    public static ArrayList<String> formulaList = new ArrayList<>();

    public static ArrayList<String> formulaListOther = new ArrayList<>();

    public static void main(String[] args) {

        int i = 0;
        while(i < 100000) {
            // 算式生成 三个运算数 确认 结果
            new MathAddSubPractice().questionGenToConfirmResult(6);
            new MathAddSubPractice().questionGenToConfirmResult(new Random().nextInt(3));
            i++;
        }

        // 保证一行两个
        if (formulaList.size() % 2 !=0) {
            formulaList.remove(formulaList.size()-1);
        }

        // 保证一行两个
        if (formulaListOther.size() % 2 !=0) {
            formulaListOther.remove(formulaListOther.size()-1);
        }

        int count1 =  formulaList.size() / 44;
        int count2 =  formulaListOther.size() / 44;

        int countMin = Math.min(count1, count2);

        for (int k = 0; k < countMin; k++) {
            // 算式输出
            for (int j = 0; j < 44; j = j + 2 ) {
                String formula1 = formulaList.get(j + k * 44);
                String formula2 = formulaList.get(j + 1 + k * 44);
                System.out.printf("%s    |    %s%n", formula1, formula2);
            }

            for (int j = 0; j < 44; j = j + 2 ) {
                String formula1 = formulaListOther.get(j + k * 44);
                String formula2 = formulaListOther.get(j + 1 + k * 44);
                System.out.printf("%s    |    %s%n", formula1, formula2);
            }
        }

        // 运算数 算子 统计
        for (Map.Entry<Object, Integer> entry : OPERATOR_COUNT.entrySet()) {
            String count = String.format("%s : %d", entry.getKey(), entry.getValue());
            System.out.println(count);
        }
    }


    /**
     * 算式生成 三个运算数 确认 结果
     * xIndex 求值索引 6: 最后结果; 1, 2, 3 操作数
     */
    public void questionGenToConfirmResult(int xIndex) {
        // 随机 加减 操作符
        int ran1 = new Random().nextInt(2);
        int ran2 = new Random().nextInt(2);

        // 加减操作符 三个 操作数
        String operator1 = "*";
        int operand1 = new Random().nextInt(19) + 1;
        String[] operator2 = new String[]{"+", "-"};
        int operand2 = new Random().nextInt(19) + 1;
        String[] operator3 = new String[]{"+", "-"};
        int operand3 = new Random().nextInt(19) + 1;
        int result = new Random().nextInt(19) + 1;

        // 操作符 操作数 列表
        List<Object> mathList = new ArrayList<>();

        mathList.add(operand1);
        mathList.add(operand2);
        mathList.add(operand3);
        mathList.add(operator1);
        mathList.add(operator2[ran1]);
        mathList.add(operator3[ran2]);
        mathList.add(result);

        int operand12 = compute((int)mathList.get(0), (int)mathList.get(1), (String)mathList.get(4));
        int operand123 = compute(operand12, (int)mathList.get(2), (String)mathList.get(5));

        if (operand123 == result && operand12 > 0 && operand12 < 20) {
            // 统计 运算数 算子
            for (Object o : mathList) {
                if (OPERATOR_COUNT.containsKey(o)) {
                    OPERATOR_COUNT.put(o, OPERATOR_COUNT.get(o) + 1);
                }
            }
            // 随机 求值 的位置
            mathList.set(xIndex, "(   )");
            String formula = String.format("%2s %2s %2s %2s %2s = %2s", mathList.get(0), mathList.get(4), mathList.get(1), mathList.get(5), mathList.get(2), mathList.get(6));

            if (xIndex == 6) {
                formulaList.add(formula);
            } else {
                formulaListOther.add(formula);
            }
        }
    }


    /**
     * 加减法计算
     * @param a 运算数1
     * @param b 运算数2
     * @param x 操作符
     * @return 结果
     */
    public int compute(int a, int b, String x) {
        if (Objects.equals(x, "+")) {
            return Math.addExact(a, b);
        }
        return Math.subtractExact(a, b);
    }
}