2024牛客寒假训练营第3场补题

写在前面

直播讲题给的总体难度如下图(对标区域赛)：

图片.png

这场算是遇到短板了吧，比赛时时间安排上也有问题，打的比较烂，好好补补吧。

L、M-智乃的36倍数_2024牛客寒假算法基础集训营3 (nowcoder.com)

题目大意

题目分析

python code

import sys

input = sys.stdin.readline


def solve() -> None:
    n = int(input())
    a = list(map(int, input().split()))
    cnt = [[0] * 10 for _ in range(110)]
    # 开桶计数
    for i in range(n):
        if a[i] < 10:
            cnt[100 + a[i]][a[i] % 9] += 1
            continue
        bit, now = 0, a[i]
        while now:
            bit += now % 10
            now //= 10
        cnt[a[i] % 100][bit % 9] += 1
    # 统计答案
    ans = 0
    for i in range(110):  # 后面
        for j in range(10):
            for k in range(110):
                for m in range(10):
                    if (i < 100 and i % 4 != 0) or (j + m) % 9 != 0: continue
                    if i >= 100 and (i - 100 + k * 10) % 4 != 0: continue
                    ans += cnt[i][j] * cnt[k][m]

    # 减去自己和自己拼的情况
    for i in range(n):
        if a[i] % 4 == 0 and a[i] % 9 == 0: ans -= 1

    print(ans)

solve()

G、H-智乃的比较函数(normal version)_2024牛客寒假算法基础集训营3 (nowcoder.com)

题目大意

题目分析

easy版本的只有两个限制条件，直接分情况讨论即可。

总结

​ 有时候做题不一定得按着出题人给的逻辑想，当按照题目给的逻辑很难想时或是想了很久时，考虑换个角度可能就出来了。

python code

easy version

import sys
input = sys.stdin.readline


def solve():
    n = int(input())
    if n == 1:
        x,y,z = map(int, input().split())
        if x == y and z == 1:
            print("No")
            return
        print("Yes")
        return

    """n == 2"""
    x, y, z = map(int, input().split())
    a, b, c = map(int, input().split())
    if x == a and y == b and c != z:
        print("No")
        return
    if a == y and b == x and c != 0 and z != 0:
        print("No")
        return
    if (a == b and c == 1) or (x == y and z == 1):
        print("No")
        return
    print("Yes")


for _ in range(int(input())):
    solve()

hard version

import sys
input = sys.stdin.readline

def solve():
    n = int(input())
    ls = []
    for i in range(1,4):
        for j in range(1,4):
            for k in range(1,4):
                ls.append((i,j,k))
    vis = [[0]*n for _ in range(27)]

    for j in range(n):
        x,y,z = map(int, input().split())
        for i in range(27):
            if z == 1 and ls[i][x-1] < ls[i][y-1]:
                vis[i][j] = 1
            if z == 0 and ls[i][x-1] >= ls[i][y-1]:
                vis[i][j] = 1

    for i in range(27):
        if sum(vis[i]) == n:
            print("Yes")
            return
    print("No")

for _ in range(int(input())):
    solve()