CSU-1982 小M的移动硬盘

CSU-1982 小M的移动硬盘

Description

最近小M买了一个移动硬盘来储存自己电脑里不常用的文件。但是他把这些文件一股脑丢进移动硬盘后，觉得这些文件似乎没有被很好地归类，这样以后找起来岂不是会非常麻烦？
小M最终决定要把这些文件好好归类，把同一类地移动到一起。所以现在小M有了这几种操作：
1 u 表示把编号为u的文件放到最上面
2 u 表示把编号为u的文件放到最下面
3 u v 表示把编号为u的文件放到编号为v的文件的后面
已知在最开始的时候，1号文件到n号文件从上往下排布
现在小M已经给出了他所进行的所有操作，你能告诉他操作之后的序列是会变成什么样子吗？

Input

第一行为一个数字T（T<=10）表示数据组数
第二行为两个数字n、m（1<=n,m<=300000）表示序列长度和小M的操作次数
接下来m行每行两个或三个数字，具体含义见题面
保证数据合法

Output

输出一行表示小M操作结束后的序列

Sample Input

1
10 5
1 5
2 3
2 6
3 4 8
3 1 3

Sample Output

5 2 7 8 4 9 10 3 1 6

---

题解

也是一道水题，但却WA了很多发，这题用数组模拟双向链表即可，先贴一开始WA的代码

#include<bits/stdc++.h>
#define maxn 300050
using namespace std;
struct node {int l, r;
} a[maxn];
int main() {int t;scanf("%d", &t);while (t--) {int n, m;scanf("%d%d", &n, &m);for (int i = 1; i <= n; i++) {a[i].l = i - 1;a[i].r = i + 1;}int head = 1, tail = n;for (int i = 1; i <= m; i++) {int q;scanf("%d", &q);if (q == 1) {int x;scanf("%d", &x);if (x == head) continue;if (x == tail) tail = a[x].l;a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[head].l = x;a[x].l = 0;a[x].r = head;head = x;}if (q == 2) {int x;scanf("%d", &x);if (x == tail) continue;if (x == head) head = a[x].r;a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[tail].r = x;a[x].l = tail;a[x].r = n + 1;tail = x;}if (q == 3) {int x, y;scanf("%d%d", &x, &y);if (x == y) continue;if (x == head) {head = a[x].r;}if (y == tail) {tail = x;}a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[x].r = a[y].r;a[a[y].r].l = x;a[x].l = y;a[y].r = x;}}int now = head;for (int i = 1; i < n; i++) {printf("%d ", now);now = a[now].r;}printf("%d\n", now);}return 0;
}
/**********************************************************************Problem: 1982User: ArtoriaxLanguage: C++Result: WA
**********************************************************************/

这个代码只有一点没注意到，即在q==3时，x处于tail时也会导致tail变化，很容易想的一个点，但却WA了很多次，然后去网上搜题解，用a[0]表示链表头，用a[n + 1]表示表尾才AC, 之后对拍一发才发现这个愚蠢的错误。

---

网上题解版：

#include<bits/stdc++.h>
#define maxn 300050
using namespace std;
struct node {int l, r;
} a[maxn];
int main() {int t;scanf("%d", &t);while (t--) {int n, m;scanf("%d%d", &n, &m);for (int i = 1; i <= n; i++) {a[i].l = i - 1;a[i].r = i + 1;}a[0].r = 1;a[n + 1].l = n;for (int i = 1; i <= m; i++) {int q;scanf("%d", &q);if (q == 1) {int x;scanf("%d", &x);a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[x].l = 0;a[x].r = a[0].r;a[a[0].r].l = x;a[0].r = x;}if (q == 2) {int x;scanf("%d", &x);a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[x].r = n + 1;a[x].l = a[n + 1].l;a[a[n + 1].l].r = x;a[n + 1].l = x;}if (q == 3) {int x, y;scanf("%d%d", &x, &y);if (x == y) continue;a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[x].r = a[y].r;a[a[y].r].l = x;a[x].l = y;a[y].r = x;}}int now = a[0].r;for (int i = 1; i < n; i++) {printf("%d ", now);now = a[now].r;}printf("%d\n", now);}return 0;
}
/**********************************************************************Problem: 1982User: ArtoriaxLanguage: C++Result: ACTime:556 msMemory:4368 kb
**********************************************************************/

自己改正版:

#include<bits/stdc++.h>
#define maxn 300050
using namespace std;
struct node {int l, r;
} a[maxn];
int main() {int t;scanf("%d", &t);while (t--) {int n, m;scanf("%d%d", &n, &m);for (int i = 1; i <= n; i++) {a[i].l = i - 1;a[i].r = i + 1;}int head = 1, tail = n;for (int i = 1; i <= m; i++) {int q;scanf("%d", &q);if (q == 1) {int x;scanf("%d", &x);if (x == head) continue;if (x == tail) tail = a[x].l;a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[head].l = x;a[x].l = 0;a[x].r = head;head = x;}if (q == 2) {int x;scanf("%d", &x);if (x == tail) continue;if (x == head) head = a[x].r;a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[tail].r = x;a[x].l = tail;a[x].r = n + 1;tail = x;}if (q == 3) {int x, y;scanf("%d%d", &x, &y);if (x == y) continue;if (a[y].r == x) continue;if (x == head) {head = a[x].r;}if (x == tail) {tail = a[x].l;}if (y == tail) {tail = x;}a[a[x].l].r = a[x].r;a[a[x].r].l = a[x].l;a[x].r = a[y].r;a[a[y].r].l = x;a[x].l = y;a[y].r = x;}}int now = head;for (int i = 1; i < n; i++) {printf("%d ", now);now = a[now].r;}printf("%d\n", now);}return 0;
}
/**********************************************************************Problem: 1982User: ArtoriaxLanguage: C++Result: ACTime:560 msMemory:4368 kb
**********************************************************************/