NOIP2023模拟16联测37 D. 小猫吃火龙果

• NOIP2023模拟16联测37 D. 小猫吃火龙果
  • 题目大意
  • 思路
  • code

题目大意

有 \(n\) 个物品 \(A\) , \(B\) , \(C\) ，\(A\) 吃 \(B\)，\(B\) 吃 \(C\)，\(C\) 吃 \(A\)，有两种操作，给 \([ l , r ]\) 的 \(x , y\) 互换，求出经过操作后得出什么。

\(n , m \le 2\times10^5\)

思路

分块

维护一个状态 \(c_i\) 表示这个块的 \(A , B , C\) 分别变成了什么。

再维护一个 \(to_{id , x , y}\) 第 \(id\) 块，状态为 \(x\)，把 \(y\) 带进去会带出来什么。

code

#include <bits/stdc++.h>
#define fu(x , y , z) for(int x = y ; x <= z ; x ++)
#define get_next(now , x) (now == (x + 1) % 3 ? x : now)
using namespace std;
const int N = 2e5 + 5;
int n , m , a[N] , block , to[N][6][3] , t[N];
int c[6][3] = {{0 , 1 , 2} , {0 , 2 , 1} , {1 , 0 , 2} , {1 , 2 , 0} , {2 , 0 , 1} , {2 , 1 , 0}};
int b[6][3] = {{2 , 5 , 1} , {3 , 4 , 0} , {0 , 3 , 4} , {1 , 2 , 5} , {5 , 1 , 2} , {4 , 0 , 3}};
inline int read () {
    char ch = getchar ();
    while (ch != 'A' && ch != 'B' && ch != 'C') ch = getchar ();
    return ch - 'A';
}
// inline int get_next (int now , int x) {
//     if (now == (x + 1) % 3) return x;
//     else return now;
// }
inline void updata (int id) {
    int l = id * block + 1 , r = min ((id + 1) * block , n);
    fu (i , 0 , 5) {
        fu (j , 0 , 2) {
            to[id][i][j] = j;
            fu (k , l , r) 
                to[id][i][j] = get_next (to[id][i][j] , c[i][a[k]]);
        }
    }
}
inline void renew (int id) {
    int l = id * block + 1 , r = min ((id + 1) * block , n);
    fu (i , l , r) a[i] = c[t[id]][a[i]];
    t[id] = 0;
}
inline int rd () {
    int val = 0;
    char ch = getchar ();
    while (ch < '0' || ch > '9') ch = getchar ();
    while (ch >= '0' && ch <= '9') {
        val = val * 10 + (ch - '0');
        ch = getchar ();
    }
    return val;
}
int main () {
    freopen ("training.in" , "r" , stdin);
    freopen ("training.out" , "w" , stdout);
    int x , y , l , r , op , minr , id , type;
    n = rd () , m = rd ();
    fu (i , 1 , n) a[i] = read ();
    if(n>100)block = sqrt (n / 12);
    else block=sqrt(n);
    fu (i , 0 , (n + block - 1) / block) 
        updata (i);
    while (m --) {
        op = rd () , l = rd () , r = rd ();
        if (op) {
            x = read ();
            id = (l - 1) / block;
            minr = min ((l - 1) / block * block + block , r);
            while (l <= minr) {
                x = get_next (x , c[t[id]][a[l]]);
                l ++;
            }
            while (l <= r - block + 1) {
                id = (l - 1) / block;
                x = to[id][t[id]][x];
                l += block;
            }
            id = (l - 1) / block;
            while (l <= r) {
                x = get_next (x , c[t[id]][a[l]]);
                l ++;
            }
            printf ("%c\n" , x + 'A');
        }
        else {
            x = read () , y = read ();
            if (x == y) continue;
            if (x > y) swap (x , y);
            id = (l - 1) / block;
            minr = min ((l - 1) / block * block + block , r);
            type = (x == 0 ? y == 1 ? 0 : 1 : 2);
            renew (id);
            while (l <= minr) {
                if (a[l] == x) a[l] = y;
                else if (a[l] == y) a[l] = x;
                l ++;
            }
            updata (id);
            while (l <= r- block + 1) {
                id = (l - 1) / block;
                t[id] = b[t[id]][type];
                l += block;
            }
            renew (id = (l - 1) / block);
            while (l <= r) {
                if (a[l] == x) a[l] = y;
                else if (a[l] == y) a[l] = x;
                l ++;
            }
            updata (id);
        }
    }
    return 0;
}