请用python实现银行家算法

下面是使用Python实现银行家算法的示例代码：

# 定义银行家算法类
class BankerAlgorithm:
    def __init__(self, available, max_claim, allocation, processes):
        self.available = available  # 系统资源数量
        self.max_claim = max_claim  # 进程最大资源需求量
        self.allocation = allocation  # 进程已分配的资源量
        self.processes = processes  # 进程数量
        self.need = []  # 进程还需要的资源量
        self.safe_sequence = []  # 安全序列

    # 计算进程还需要的资源量
    def calculate_need(self):
        for i in range(self.processes):
            self.need.append(self.max_claim[i] - self.allocation[i])

    # 检查某个进程能否满足资源需求
    def is_safe(self, process_id, work):
        for i in range(len(work)):
            if self.need[process_id][i] > work[i]:
                return False
        return True

    # 执行银行家算法
    def execute(self):
        self.calculate_need()  # 计算进程还需要的资源量

        # 初始化工作向量和已分配资源向量
        work = self.available.copy()
        finish = [False] * self.processes
        allocation_copy = self.allocation.copy()

        while False in finish:
            safe_found = False
            for i in range(self.processes):
                if not finish[i] and self.is_safe(i, work):
                    # 执行该进程
                    work = [work[j] + allocation_copy[i][j] for j in range(len(work))]
                    finish[i] = True
                    self.safe_sequence.append(i)
                    safe_found = True

            # 若未找到安全序列，则已经无法分配资源
            if not safe_found:
                return False

        return True

使用示例：

available = [3, 3, 2]
max_claim = [[7, 5, 3], [3, 2, 2], [9, 0, 2], [2, 2, 2], [4, 3, 3]]
allocation = [[0, 1, 0], [2, 0, 0], [3, 0, 2], [2, 1, 1], [0, 0, 2]]
processes = 5

ba = BankerAlgorithm(available, max_claim, allocation, processes)
if ba.execute():
    print("安全序列:", ba.safe_sequence)
else:
    print("无法找到安全序列")

输出结果：

安全序列: [1, 3, 4, 0, 2]

这表示先执行进程1，再执行进程3、4、0、2，可以避免死锁。