DPLL算法回溯树的c++文件和方法是什么？

#include <iostream>
#include <vector>

using namespace std;

// 定义变量状态的枚举类型
enum class VarState {
    UNASSIGNED,
    TRUE,
    FALSE
};

// 定义子句的结构体
struct Clause {
    vector<int> literals;
};

// DPLL算法的回溯函数
bool dpll(vector<Clause>& clauses, vector<VarState>& assignment) {
    // 检查是否所有子句都被满足
    bool allClausesSatisfied = true;
    for (const auto& clause : clauses) {
        bool clauseSatisfied = false;
        for (const auto& literal : clause.literals) {
            int var = abs(literal);
            bool isNegated = (literal < 0);
            if ((assignment[var] == VarState::TRUE && !isNegated) ||
                (assignment[var] == VarState::FALSE && isNegated)) {
                clauseSatisfied = true;
                break;
            }
        }
        if (!clauseSatisfied) {
            allClausesSatisfied = false;
            break;
        }
    }

    // 如果所有子句都被满足，则返回true
    if (allClausesSatisfied) {
        return true;
    }

    // 查找未赋值的变量
    int unassignedVar = -1;
    for (int i = 1; i < assignment.size(); i++) {
        if (assignment[i] == VarState::UNASSIGNED) {
            unassignedVar = i;
            break;
        }
    }

    // 如果没有未赋值的变量，则返回false
    if (unassignedVar == -1) {
        return false;
    }

    // 递归地尝试给未赋值的变量赋值
    assignment[unassignedVar] = VarState::TRUE;
    if (dpll(clauses, assignment)) {
        return true;
    }
    assignment[unassignedVar] = VarState::FALSE;
    if (dpll(clauses, assignment)) {
        return true;
    }
    assignment[unassignedVar] = VarState::UNASSIGNED;

    return false;
}

int main() {
    // 构造逻辑公式的子句集合
    vector<Clause> clauses = {
        {{1, 2}},   // (x1 ∨ x2)
        {{-1, 3}},  // (¬x1 ∨ x3)
        {{-2, -3}}  // (¬x2 ∨ ¬x3)
    };

    // 初始化变量赋值状态
    vector<VarState> assignment(4, VarState::UNASSIGNED);

    // 调用DPLL算法求解
    bool isSatisfiable = dpll(clauses, assignment);

    // 输出结果
    if (isSatisfiable) {
        cout << "The formula is satisfiable." << endl;
        cout << "Variable assignment: ";
        for (int i = 1; i < assignment.size(); i++) {
            cout << "x" << i << "=" << (assignment[i] == VarState::TRUE ? "true" : "false") << " ";
        }
        cout << endl;
    } else {
        cout << "The formula is unsatisfiable." << endl;
    }

    return 0;
}