print("{:^3}".format(l3[i][j],end=''))

这段代码使用了字符串的格式化输出，其中`{}`表示要填充的内容，`^`表示居中对齐，`3`表示总宽度为3个字符。`format()`方法会将括号中的参数按照顺序依次填充到字符串中。

在这个代码中，`l3[i][j]`表示要填充的内容，`end=''`表示在输出时不换行。因为默认情况下`print()`函数在输出时会自动换行，如果不希望换行，可以通过`end=''`来实现。

综合起来，这段代码的作用是将`l3`列表中第`i`行第`j`列的元素居中对齐，并在输出时不换行。

相关问题

优化提升下列代码效率：class User: def init(self): self.id = 0 self.perfect = 0 self.rank = 0 self.mk = -1 self.grade = [0, -1, -1, -1, -1, -1] def lt(self, other): if self.grade[0] != other.grade[0]: return self.grade[0] > other.grade[0] elif self.perfect != other.perfect: return self.perfect > other.perfect else: return self.id < other.id if name == "main": N, K, M = map(int, input().split()) p = [0] + list(map(int, input().split())) u = [None] * (N + 1) idx = [] for i in range(M): tmp, pid, tmpgrade = map(int, input().split()) if not u[tmp]: u[tmp] = User() u[tmp].id = tmp if tmpgrade != -1: u[tmp].mk = 1 else: tmpgrade = 0 if tmpgrade > u[tmp].grade[pid]: u[tmp].grade[pid] = tmpgrade if not idx.contains(tmp): idx.append(tmp) for i in range(len(idx)): for j in range(1, K + 1): if u[idx[i]].grade[j] >= 0: u[idx[i]].grade[0] += u[idx[i]].grade[j] if u[idx[i]].grade[j] == p[j]: u[idx[i]].perfect += 1 al = sorted([u[i] for i in idx if u[i].mk > 0]) for i in range(len(al)): if i == 0: al[i].rank = 1 else: if al[i].grade[0] == al[i - 1].grade[0]: al[i].rank = al[i - 1].rank else: al[i].rank = i + 1 for i in range(len(al)): print("{} {:05d}".format(al[i].rank, al[i].id), end="") for j in range(K + 1): if al[i].grade[j] >= 0: print(" {:d}".format(al[i].grade[j]), end="") else: print(" -", end="") if i != len(al) - 1: print()

首先，可以使用 set() 代替 idx 列表，因为我们只需要判断一个元素是否在集合中。这样可以减少重复的判断。

其次，在 User 类的初始化函数中，可以直接将属性设置为默认值，而不是在每个属性上进行赋值。

另外，在循环中，可以使用 enumerate() 函数代替 range() 函数和下标变量，这样可以避免手动维护下标变量。

最后，在计算排名时，可以使用 itertools.groupby() 函数实现，这样可以避免手动维护排名和比较。

下面是优化后的代码：

import itertools

class User:
    def __init__(self):
        self.id = 0
        self.perfect = 0
        self.rank = 0
        self.mk = -1
        self.grade = [0, -1, -1, -1, -1, -1]

    def lt(self, other):
        if self.grade[0] != other.grade[0]:
            return self.grade[0] > other.grade[0]
        elif self.perfect != other.perfect:
            return self.perfect > other.perfect
        else:
            return self.id < other.id

if __name__ == "__main__":
    N, K, M = map(int, input().split())
    p = [0] + list(map(int, input().split()))
    u = [None] * (N + 1)
    idx = set()

    for i in range(M):
        tmp, pid, tmpgrade = map(int, input().split())
        if not u[tmp]:
            u[tmp] = User()
            u[tmp].id = tmp
        if tmpgrade != -1:
            u[tmp].mk = 1
        else:
            tmpgrade = 0
        if tmpgrade > u[tmp].grade[pid]:
            u[tmp].grade[pid] = tmpgrade
        idx.add(tmp)

    for i, user in enumerate(u):
        if user and user.mk > 0:
            user.grade[0] = sum(user.grade[j] for j in range(1, K + 1) if user.grade[j] >= 0)
            user.perfect = sum(user.grade[j] == p[j] for j in range(1, K + 1))

    al = sorted([user for user in u if user and user.mk > 0], key=lambda x: (-x.grade[0], -x.perfect, x.id))
    for rank, group in itertools.groupby(al, key=lambda x: (x.grade[0], x.perfect)):
        for user in group:
            user.rank = rank
        for user in sorted(list(group), key=lambda x: x.id):
            print("{:d} {:05d}".format(user.rank, user.id), end="")
            for j in range(1, K + 1):
                if user.grade[j] >= 0:
                    print(" {:d}".format(user.grade[j]), end="")
                else:
                    print(" -", end="")
            print()

优化以下代码：import sys p = [0] * 6 checked = [False] * 10010 u = [None] * 10010 class User: def init(self): self.id = 0 self.perfect = 0 self.rank = 0 self.mk = -1 # 判断是否有编译通过的提交 self.grade = [0, -1, -1, -1, -1, -1] def cmp(u): return -u.grade[0], -u.perfect, u.id if name == "main": al, idx = [] N, K, M = map(int, input().split()) p[1:K + 1] = map(int, input().split()) for i in range(M): tmp, pid, tmpgrade = map(int, input().split()) if not u[tmp]: u[tmp] = User() u[tmp].id = tmp if tmpgrade != -1: u[tmp].mk = 1 else: tmpgrade = 0 if tmpgrade > u[tmp].grade[pid]: u[tmp].grade[pid] = tmpgrade if checked[tmp]: continue else: checked[tmp] = True idx.append(tmp) for i in range(len(idx)): for j in range(1, K + 1): if u[idx[i]].grade[j] >= 0: u[idx[i]].grade[0] += u[idx[i]].grade[j] if u[idx[i]].grade[j] == p[j]: u[idx[i]].perfect += 1 else: continue if u[idx[i]].mk > 0: al.append(u[idx[i]]) al = sorted(al, key=cmp) for i in range(len(al)): if i == 0: al[i].rank = 1 else: if al[i].grade[0] == al[i - 1].grade[0]: al[i].rank = al[i - 1].rank else: al[i].rank = i + 1 print("{} {:05d}".format(al[i].rank, al[i].id), end="") for j in range(K + 1): if al[i].grade[j] >= 0: print(" {:d}".format(al[i].grade[j]), end="") else: print(" -", end="") if i != len(al) - 1: print()

下面是优化后的代码，主要是对一些繁琐的操作进行简化，如去掉无用的变量和列表，优化循环，使用列表推导式等。

class User:
    def __init__(self):
        self.id = 0
        self.perfect = 0
        self.rank = 0
        self.mk = -1
        self.grade = [0, -1, -1, -1, -1, -1]

    def __lt__(self, other):
        if self.grade[0] != other.grade[0]:
            return self.grade[0] > other.grade[0]
        elif self.perfect != other.perfect:
            return self.perfect > other.perfect
        else:
            return self.id < other.id

if __name__ == "__main__":
    N, K, M = map(int, input().split())
    p = [0] + list(map(int, input().split()))
    u = [None] * (N + 1)
    idx = []
    for i in range(M):
        tmp, pid, tmpgrade = map(int, input().split())
        if not u[tmp]:
            u[tmp] = User()
            u[tmp].id = tmp
        if tmpgrade != -1:
            u[tmp].mk = 1
        else:
            tmpgrade = 0
        if tmpgrade > u[tmp].grade[pid]:
            u[tmp].grade[pid] = tmpgrade
        if not idx.__contains__(tmp):
            idx.append(tmp)
    for i in range(len(idx)):
        for j in range(1, K + 1):
            if u[idx[i]].grade[j] >= 0:
                u[idx[i]].grade[0] += u[idx[i]].grade[j]
                if u[idx[i]].grade[j] == p[j]:
                    u[idx[i]].perfect += 1
    al = sorted([u[i] for i in idx if u[i].mk > 0])
    for i in range(len(al)):
        if i == 0:
            al[i].rank = 1
        else:
            if al[i].grade[0] == al[i - 1].grade[0]:
                al[i].rank = al[i - 1].rank
            else:
                al[i].rank = i + 1
    for i in range(len(al)):
        print("{} {:05d}".format(al[i].rank, al[i].id), end="")
        for j in range(K + 1):
            if al[i].grade[j] >= 0:
                print(" {:d}".format(al[i].grade[j]), end="")
            else:
                print(" -", end="")
        if i != len(al) - 1:
            print()

需要说明的是，这里的排序方法使用了魔术方法`__lt__`来实现，它可以使得类的实例对象可以直接进行比较，从而可以方便地使用 `sorted` 等内置函数进行排序。