java 传一个入参total，在递归方法中做累加计算,计算完成后，获取计算好的total

可以将total作为参数传递给递归方法，并在每次递归调用时进行累加操作。当递归结束后，方法会返回最终的total值。示例代码如下：

public int calculateTotal(int n, int total) {
    if (n == 0) {
        return total;
    }
    total += n;
    return calculateTotal(n - 1, total);
}

在调用该方法时，需要传入两个参数：n表示递归的次数，total表示累加的初始值。例如：

int result = calculateTotal(10, 0);
System.out.println(result); // 输出55

上述代码会将1到10的数累加起来，最终输出55。

相关问题

java 实现 父子部门的人数 ,父部门人数 为各子部门人数总和 ,和输出各自节点人数

假设我们有一个部门树形结构，每个节点包含一个部门对象和一个子节点列表。部门对象中包含一个部门名称和一个人数。

首先我们需要定义一个递归函数来计算每个节点的人数：

public int calculateTotalEmployees(DepartmentNode node) {
    int total = node.getDepartment().getEmployeeCount();
    for (DepartmentNode child : node.getChildren()) {
        total += calculateTotalEmployees(child);
    }
    node.getDepartment().setEmployeeCount(total); // 更新当前节点的员工数
    return total;
}

这个函数首先会获取当前节点的员工数，然后递归调用子节点的这个函数，并将子节点的返回值累加到总人数中。最后更新当前节点的员工数并返回总人数。

接下来我们可以遍历整个部门树，对每个节点调用上面的函数来计算员工数：

public void printDepartmentEmployeeCount(DepartmentNode root) {
    calculateTotalEmployees(root); // 先计算每个节点的员工数
    printEmployeeCount(root); // 输出每个节点的员工数
}

private void printEmployeeCount(DepartmentNode node) {
    System.out.println(node.getDepartment().getName() + ": " + node.getDepartment().getEmployeeCount());
    for (DepartmentNode child : node.getChildren()) {
        printEmployeeCount(child);
    }
}

这个函数会先调用 `calculateTotalEmployees` 函数来计算每个节点的员工数，然后遍历整个部门树，输出每个节点的员工数。注意输出时要输出节点名称和员工数。

完整代码如下：

public class DepartmentNode {
    private Department department;
    private List<DepartmentNode> children;

    public DepartmentNode(Department department) {
        this.department = department;
        children = new ArrayList<>();
    }

    public Department getDepartment() {
        return department;
    }

    public void addChild(DepartmentNode child) {
        children.add(child);
    }

    public List<DepartmentNode> getChildren() {
        return children;
    }
}

public class Department {
    private String name;
    private int employeeCount;

    public Department(String name, int employeeCount) {
        this.name = name;
        this.employeeCount = employeeCount;
    }

    public String getName() {
        return name;
    }

    public int getEmployeeCount() {
        return employeeCount;
    }

    public void setEmployeeCount(int employeeCount) {
        this.employeeCount = employeeCount;
    }
}

public class Main {
    public static void main(String[] args) {
        DepartmentNode root = new DepartmentNode(new Department("总部", 0));
        DepartmentNode child1 = new DepartmentNode(new Department("子部门1", 10));
        DepartmentNode child2 = new DepartmentNode(new Department("子部门2", 20));
        DepartmentNode child3 = new DepartmentNode(new Department("子部门3", 30));
        root.addChild(child1);
        root.addChild(child2);
        root.addChild(child3);
        DepartmentNode grandChild1 = new DepartmentNode(new Department("孙子部门1", 5));
        DepartmentNode grandChild2 = new DepartmentNode(new Department("孙子部门2", 15));
        DepartmentNode grandChild3 = new DepartmentNode(new Department("孙子部门3", 25));
        child1.addChild(grandChild1);
        child2.addChild(grandChild2);
        child3.addChild(grandChild3);
        Main main = new Main();
        main.printDepartmentEmployeeCount(root);
    }

    public int calculateTotalEmployees(DepartmentNode node) {
        int total = node.getDepartment().getEmployeeCount();
        for (DepartmentNode child : node.getChildren()) {
            total += calculateTotalEmployees(child);
        }
        node.getDepartment().setEmployeeCount(total); // 更新当前节点的员工数
        return total;
    }

    public void printDepartmentEmployeeCount(DepartmentNode root) {
        calculateTotalEmployees(root); // 先计算每个节点的员工数
        printEmployeeCount(root); // 输出每个节点的员工数
    }

    private void printEmployeeCount(DepartmentNode node) {
        System.out.println(node.getDepartment().getName() + ": " + node.getDepartment().getEmployeeCount());
        for (DepartmentNode child : node.getChildren()) {
            printEmployeeCount(child);
        }
    }
}