for i in range(n): a=list(map(int,input().split()))哪里错了

这段代码没有明确错误，但需要知道输入的n是什么。如果n没有定义或赋值，那么代码会报错。另外，应该在代码前加上提示，告诉用户需要输入什么样的值。例如：

n = int(input("请输入一个整数："))
for i in range(n):
a = list(map(int, input().split()))
print(a)

相关问题

约瑟夫环改错class Node: def __init__(self,data): self.data=data self.next=Noneclass linklist: def __init__(self): self.head=None self.data=None def isEmpty(self): if self.head: return False else: return True def length(self): if self.isEmpty(): return 0 else: t = self.head n = 1 while t.next: if t.next == self.head: break t = t.next n = n + 1 return n def addhead(self,data): node = Node(data) if self.isEmpty(): self.head = node self.tail = self.head else: node.next = self.head self.head = node self.tail.next = self.head def addtail(self,data): node=Node(data) if self.isEmpty(): self.addhead(data) else: t=self.head n=1 l=self.length() while n<l: n=n+1 t=t.next t.next=node node.next=self.head self.tail=node def delete(self,index): if self.isEmpty(): print("The linked list is empty") else: t = self.head l = self.length() if index == 0: self.head = t.next self.tail.next = self.head elif index == l - 1: n = 1 while n < l - 1: t = t.next n = n + 1 t.next = self.head self.tail = t elif index > l - 1: print("Out of range") elif index < 0: print("Wrong operation") else: n = 1 while n < index - 1: t = t.next n = n + 1 a = t.next.next t.next = a def insert(self,data,index): l = self.length() if index == 0 or self.isEmpty(): self.addhead(data) elif index >= l: self.addtail(data) else: node = Node(data) t = self.head n = 1 while n < index - 1: t = t.next n = n + 1 a = t.next t.next = node node.next = a def search(self,a): t=self.head for i in range(a): t=t.next return t.data def form(self,datalist): self.addhead(datalist[0]) for i in range(1,len(datalist)): self.addtail(datalist[i]) t = self.head while t.next != self.head: t = t.nextn,p=map(int,input().split(' '))data=[]p=p-1for i in range(1,n+1): data.append(i)print(data)datalist=[]for i in range(len(data)): datalist.append(int(data[i]))link=linklist()link.form(datalist)a=pb=[]while link.length()>0: b.append(link.search(a)) link.delete(a) a=a+p while a>=link.length(): a=a-link.length()print(b)

改错如下：

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

class LinkList:
    def __init__(self):
        self.head = None
        self.tail = None
    
    def isEmpty(self):
        if self.head:
            return False
        else:
            return True
    
    def length(self):
        if self.isEmpty():
            return 0
        else:
            t = self.head
            n = 1
            while t.next:
                if t.next == self.head:
                    break
                t = t.next
                n += 1
            return n
    
    def addhead(self, data):
        node = Node(data)
        if self.isEmpty():
            self.head = node
            self.tail = self.head
        else:
            node.next = self.head
            self.head = node
            self.tail.next = self.head
    
    def addtail(self, data):
        node = Node(data)
        if self.isEmpty():
            self.addhead(data)
        else:
            t = self.head
            n = 1
            l = self.length()
            while n < l:
                n += 1
                t = t.next
            t.next = node
            node.next = self.head
            self.tail = node
    
    def delete(self, index):
        if self.isEmpty():
            print("The linked list is empty")
        else:
            t = self.head
            l = self.length()
            if index == 0:
                self.head = t.next
                self.tail.next = self.head
            elif index == l - 1:
                n = 1
                while n < l - 1:
                    t = t.next
                    n += 1
                t.next = self.head
                self.tail = t
            elif index > l - 1:
                print("Out of range")
            elif index < 0:
                print("Wrong operation")
            else:
                n = 1
                while n < index:
                    t = t.next
                    n += 1
                a = t.next.next
                t.next = a
    
    def insert(self, data, index):
        l = self.length()
        if index == 0 or self.isEmpty():
            self.addhead(data)
        elif index >= l:
            self.addtail(data)
        else:
            node = Node(data)
            t = self.head
            n = 1
            while n < index:
                t = t.next
                n += 1
            a = t.next
            t.next = node
            node.next = a
    
    def search(self, a):
        t = self.head
        for i in range(a):
            t = t.next
        return t.data
    
    def form(self, datalist):
        self.addhead(datalist[0])
        for i in range(1, len(datalist)):
            self.addtail(datalist[i])
        t = self.head
        while t.next != self.head:
            t = t.next

n, p = map(int, input().split(' '))
data = [i for i in range(1, n+1)]
print(data)

datalist = []
for i in range(len(data)):
    datalist.append(data[i])

link = LinkList()
link.form(datalist)

a = p-1
b = []
while link.length() > 0:
    b.append(link.search(a))
    link.delete(a)
    a += p-1
    while a >= link.length():
        a -= link.length()

print(b)

优化这段代码：n=int(input()) list_a=[] sum=0 for i in range(n): row = input().split( ) list_a.append([int(x) for x in row]) for j in range(n): for k in range(n): if j==k or j+k==n-1: sum+=list_a[j][k] print("{:.2f}".format(sum))

可以使用 NumPy 库来优化这段代码，NumPy 是 Python 的一个科学计算库，它提供了高效的多维数组对象和相关工具。

以下是使用 NumPy 库优化后的代码：

import numpy as np

n = int(input())
list_a = np.zeros((n, n), dtype=int)

for i in range(n):
    row = list(map(int, input().split()))
    list_a[i] = row

sum = np.sum(list_a.diagonal()) + np.sum(np.fliplr(list_a).diagonal()) - list_a[n//2][n//2]

print("{:.2f}".format(sum))

首先，我们使用 NumPy 创建一个 $n \times n$ 的全零矩阵 `list_a`。然后，我们使用 `map` 函数和 `list` 函数将输入的字符串转换为整数列表，并将它们赋值给 `list_a` 的每一行。

接下来，我们使用 NumPy 的 `diagonal` 函数来计算矩阵的对角线元素之和。由于矩阵有两条对角线，我们需要计算它们的和。我们还需要减去中心元素的值，以避免重复计算。

最后，我们使用 `format` 函数来格式化输出结果。