避免死锁的银行家算法代码

银行家算法是一种用于避免死锁的资源分配算法。它通过判断系统是否处于安全状态来决定是否分配资源。以下是一个简单的银行家算法的伪代码示例：

# 定义资源数量和进程数量
num_resources = 3
num_processes = 5

# 初始化可用资源向量
available = [10, 5, 7]

# 初始化最大需求矩阵
max_claim = [
    [7, 5, 3],
    [3, 2, 2],
    [9, 0, 2],
    [2, 2, 2],
    [4, 3, 3]
]

# 初始化已分配资源矩阵
allocated = [
    [0, 1, 0],
    [2, 0, 0],
    [3, 0, 2],
    [2, 1, 1],
    [0, 0, 2]
]

# 初始化需求矩阵
need = [
    [7, 4, 3],
    [1, 2, 2],
    [6, 0, 0],
    [0, 1, 1],
    [4, 3, 1]
]

# 初始化完成标记向量
finished = [False] * num_processes

# 检查是否存在安全序列
def is_safe():
    work = available.copy()
    safe_sequence = []
    
    while True:
        found = False
        for i in range(num_processes):
            if not finished[i] and all(need[i][j] <= work[j] for j in range(num_resources)):
                work = [work[j] + allocated[i][j] for j in range(num_resources)]
                finished[i] = True
                safe_sequence.append(i)
                found = True
        
        if not found:
            break
    
    return all(finished)

# 请求资源
def request_resources(process_id, request):
    if all(request[i] <= need[process_id][i] for i in range(num_resources)) and all(request[i] <= available[i] for i in range(num_resources)):
        for i in range(num_resources):
            available[i] -= request[i]
            allocated[process_id][i] += request[i]
            need[process_id][i] -= request[i]
        
        if is_safe():
            return True
        else:
            # 回滚分配
            for i in range(num_resources):
                available[i] += request[i]
                allocated[process_id][i] -= request[i]
                need[process_id][i] += request[i]
    
    return False

这段代码实现了银行家算法的基本逻辑，包括判断系统是否处于安全状态和处理资源请求。你可以根据实际需求进行修改和扩展。