A Generalized ABC

• 题意：输出从’A’开始的升序的前k个英文字母
• 范围：k <= 26
• 写法：
  range(n)表示[0, n - 1]
  range(x, y)表示[x, y - 1]
  ord('A')返回’A’的Unicode编码
  chr(Unicode编码)返回对应的字符

k = int(input())
ans = ''
for i in range(k):
    ans += chr(ord('A') + i)
print(ans)

B - Let’s Get a Perfect Score

• 题意 ：n个人，m个问题，给出n个人分别的对于这m个问题是否能解决的字符串，用ox分别表示。现在从这n个人中挑出一对人，要求这两个人加起来能解决所有m个问题，问这样的对数

• 范围：
  N is an integer between 2 and 30, inclusive.
  M is an integer between 1 and 30, inclusive.

• 题解：枚举每一对，只要能找到一个位置均为x，说明这对不行

• 写法：
  输入方式“n m” n, m = map(int, input().split())
  输入n行字符串存在数组s中 s = [input() for _ in range(n)]

n, m = map(int, input().split())
s = [input() for _ in range(n)]
ans = 0
for i in range(n):
    for j in range(i + 1, n):
        ok = True
        for k in range(m):
            if s[i][k] == 'x' and s[j][k] == 'x':
                ok = False
                break
        if ok: ans += 1
print(ans)

n, m = map(int, input().split())
s = []
for i in range(n):
    s.append(input())
ans = 0
for i in range(n):
    for j in range(i + 1, n):
        ok = True
        for k in range(m):
            if s[i][k] == 'x' and s[j][k] == 'x':
                ok = False
                break
        if ok: ans += 1
print(ans)

C - String Delimiter

• 题意：给一个仅包含小写字母和逗号和双引号的字符串，保证双引号数量为偶数。定义第一个与第二个，第三个与第四个，…，双引号之间的字符为关闭的，将所有非关闭字符的逗号替换成句号并输出最终字符串
• 范围：N is an integer between 1 and 2×10^5 , inclusive.
• 写法：
  python中字符串类型是不可修改的！因此s输入为list s = list(input())
String.join(任意类型？）是将tuple中的所有东西变成字符串接在前面字符串后面

n = int(input())
s = list(input())
ok = True
for i in range(n):
    if s[i] == '"':
        ok = not ok
    elif s[i] == ',' and ok:
        s[i] = '.'
print("".join(s))

D - Make Bipartite 2