luogu_P3937 Changing

https://www.luogu.org/problem/P3937

Title Description

There are $\ n-cdots . 1 ⋯ n-. Initial time of 0 0 of the initial time i On i Off lamp a_i A i given, 0 0 for off, . 1 1 denotes light. The next time each lamp blinking lamp depending on which direction the next clockwise lamp current time blinking. If the two lights the same state, then the next time the lamp is off, otherwise the lights.$

Find the time

Input Format

The first row, three integers are

Second row, a total of $a_i A I .$

Output Format

A total line, a number,

Sample input and output

Input # 1

4 2 1
1 0 1 0

Output # 1

Description / Tips

For $\% 2 . 5 % of the data, there . 1 \ Leq T, K \ n-Leq \ Leq 1000 . 1 ≤ T , K ≤ n- ≤ . 1 0 0 0.$

For $\% . 6 0 % of the data, there . 1 \ Leq T, K \ n-Leq \ ^ Leq 10. 5 . 1 ≤ T , K ≤ n- ≤ . 1 0 . 5.$

For $\% . 1 0 0 % of the data, there . 1 \ Leq T, K \ n-Leq \ Leq. 3 * 10 ^. 6 . 1 ≤ T , K ≤ n- ≤ . 3 * . 1 0 . 6.$

$Find the next rule, we found N (log (N) / log (2)) approaches$

$Assume k = 1, we see the answer to this one$

$0$ $time, ans = a1$

$1 time, ans = a1 ^ a2$

$2 time, ANS = A1 ^ A2 ^ A3 ^ A2 = A1 ^ A3$

$3 time, ans = a1 ^ a2 ^ a3 ^ a4$

$4 时刻, = a1 's^ by ans ^ A2 ^ A2 ^ 3a , 3a ,^ ^ Forum a4 ^ A5 = Forum a4 a1 's^ A5$

$5 ......... ......... ......... ......... ......... ......... ......... ......... ......... .....$

$6 ......... ......... ......... ......... ......... ......... ......... ......... ......... ......... ..$

$7 ......... ......... ......... ......... ......... ......... ......... ......... ......... ......... .........$

$8 time, ans = ............................................. = ............................................ A1 ^ A9$

$Such log (N) / log (2) to come out, and does not in fact T$

$Multiplication and similar at the Method LCA$

#include<iostream>
#include<cstdio>

#define ri register int
#define u int

namespace opt {

    inline u in() {
        u x(0),f(1);
        char s(getchar());
        while(s<'0'||s>'9') {
            if(s=='-') f=-1;
            s=getchar();
        }
        while(s>='0'&&s<='9') {
            x=(x<<1)+(x<<3)+s-'0';
            s=getchar();
        }
        return x*f;
    }

}

using opt::in;

#include<cmath>
#include<algorithm>

#define NN 3000005

namespace mainstay {

    u N,T,K,a[NN<<1];

    inline void solve() {
        while(~scanf("%d%d%d",&N,&T,&K)) {
            for(ri i(1); i<=N; ++i) a[i]=a[i+N]=in();
            u ans(a[K]);
            while(T) {
                u k(std::log(T)/std::log(2));
                u p(std::pow(2,k));
                ans^=a[K+p];
                for(ri i(1); i<=N; ++i) a[i]^=a[i+p];
                for(ri i(1); i<=N; ++i) a[i+N]=a[i];
                T-=std::pow(2,k);
            }
            printf("%d\n",ans);
        }
    }

}

int main() {

    //freopen("TLE.in","r",stdin);
    //freopen("TLE.out","w",stdout);
    std::ios::sync_with_stdio(false);
    mainstay::solve();

}