A. Anonymous Informant

合集 - codeforces(57)

1.C. Insert and Equalize2023-12-062.C. Removal of Unattractive Pairs2023-12-063.D. Jumping Through Segments2023-12-084.E. Good Triples2023-12-085.F. Shift and Reverse2023-12-086.D. Yet Another Monster Fight2023-12-117.A. Constructive Problems2023-12-188.C. Game with Multiset2023-12-199.A. Rating Increase2023-12-1910.B. Swap and Delete2023-12-1911.A. Problemsolving Log2023-12-2012.B. Preparing for the Contest2023-12-2013.C. Quests2023-12-2014.D. Three Activities2023-12-2015.E2. Game with Marbles (Hard Version)2023-12-2016.cf刷题有感2023-12-20

17.A. Anonymous Informant2023-12-21

18.A. Forked!2023-12-2319.B. Make Almost Equal With Mod2023-12-2720.C. Heavy Intervals2023-12-2721.D. Split Plus K2023-12-2822.A. 20232023-12-3123.B. Two Divisors2023-12-3124.C. Training Before the Olympiad2023-12-3125.D. Mathematical Problem2024-01-0226.F. Greetings2024-01-0227.C. Partitioning the Array2024-01-1528.G. Bicycles2024-01-1629.E. Eat the Chip2024-01-1730.G. Lights2024-01-1731.D. Array Repetition2024-01-1732.D. Berserk Monsters2024-01-2233.E. Increasing Subsequences2024-01-2334.D. Very Different Array2024-01-2435.G. Mischievous Shooter2024-01-2536.B. Plus-Minus Split2024-01-2737.B. A Balanced Problemset2024-01-2838.C. Did We Get Everything Covered2024-01-2839.D. Find the Different Ones!2024-02-0840.C. Grouping Increases2024-02-1041.D. Good Trip2024-02-1242.C. Physical Education Lesson2024-02-1243.E. Final Countdown2024-02-1844.D. Divisible Pairs2024-02-1945.G. Vlad and Trouble at MIT2024-02-2046.A. Brick Wall2024-02-2847.B. Minimize Inversions2024-02-2848.C. XOR-distance2024-02-2849.A. Moving Chips2024-02-2850.B. Monsters Attack!2024-02-2851.C. Find B2024-02-2852.D. Slimes2024-02-2853.C. Turtle Fingers: Count the Values of k2024-02-2854.D. Turtle Tenacity: Continual Mods2024-02-2855.D. Vlad and Division2024-02-2856.C. LR-remainders2024-02-2857.D. Lonely Mountain Dungeons2024-03-12

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原题链接

前言

一道精简但是内容丰富的题

一些事实

1.循环左移len位后数组的节点对应原数组的节点，相当于在无限自复制循环的数组中将原来的节点右移len位
2.如果该数组能被定点数组循环左移x位得到，那么该数组最后一个节点的值一定是x
3.不管怎么位移，可能的数组最多只有n种不同的情况（1~n分别作为尾节点），所以可能有重复的情况
4.如果同一个节点在尾节点出现两次，说明有循环，循环内的的所有数组都是定点数组

细节

1.当k>n时，我们让k=n因为如果n次循环后的数组仍是定点数组，那么说明事实4成立

代码

#include<bits/stdc++.h>
using namespace std;
int a[200005]={0};
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int n,k;
        cin>>n>>k;
        k=min(k,n);
        for(int i=1;i<=n;i++)cin>>a[i];
        int last=n,flag=1,cf=n;
        do
        {
            if(a[last]>n)
            {
                flag=0;
                break;
            }
            last=(last-a[last]+n-1)%n+1;
        }while((--k)&&last!=cf);
        flag==1?puts("Yes"):puts("No");
    }
    return 0;
}