传送门
这是一个模拟题，因为之前做过一个分块题目，直接想错了。纠结了好久，今天上午突然明悟过来
题意
思路
看数据大小，直接模拟链表。
最前和最后添加上一个节点，这样写起来比较好
相当于复习了一遍 c 语言学的链表，写起来还是挺恶心的。
代码
1'''
2Autor: valk
3Date: 2020-08-19 18:23:25
4LastEditTime: 2020-08-25 18:21:45
5Description: 如果邪恶 是华丽残酷的乐章 它的终场 我会亲手写上 晨曦的光 风干最后一行忧伤 黑色的墨 染上安详
6'''
7class Task(object):#print
8 def solver(self, s, p, ops):
9 N = 3 * (10**5) + 10
10 pre = [0 for i in range(N)]
11 nex = [0 for i in range(N)]
12 t = [0 for i in range(N)]
13 aga = 0
14 pre[aga] = -1
15 nex[aga] = 1
16 n = len(s)
17 for i in range(len(s)):
18 t[i + 1] = s[i]
19 pre[i + 1] = i
20 nex[i + 1] = i + 2
21 en = n + 1
22 pre[en] = n
23 nex[en] = -1
24 n += 1
25 def insert(text):
26 nonlocal n, pre, nex, aga, en, t, N, p
27 rec = nex[p]
28 nex[p] = n + 1
29 pre[n + 1] = p
30 for i in range(len(text)):
31 n += 1
32 t[n] = text[i]
33 if i != 0:
34 pre[n] = n - 1
35 nex[n] = n + 1
36 nex[n] = rec
37 pre[rec] = n
38 p = n
39 def back(l):
40 nonlocal n, pre, nex, aga, en, t, N, p
41 i = 1
42 tmp = p
43 while (i <= l and pre[tmp] != -1):
44 tmp = pre[tmp]
45 i += 1
46 nex[tmp] = nex[p]
47 pre[nex[p]] = tmp
48 p = tmp
49 def delete(l):
50 nonlocal n, pre, nex, aga, en, t, N, p
51 i = 0
52 tmp = p
53 while (i <= l and nex[tmp] != -1):
54 tmp = nex[tmp]
55 i += 1
56 if tmp == p: # 特判这里，否则会死循环
57 return
58 nex[p] = tmp
59 pre[tmp] = p
60 def shiftL(l):
61 nonlocal n, pre, nex, aga, en, t, N, p
62 i = 1
63 while (i <= l and pre[p] != -1):
64 p = pre[p]
65 i += 1
66 def shiftR(l):
67 nonlocal n, pre, nex, aga, en, t, N, p
68 i = 1
69 while (i <= l and nex[p] != en):# 这里不能跑到最后一个
70 p = nex[p]
71 i += 1
72 for op in ops:
73 if op[0] == 'I':
74 insert(op[1])
75 if op[0] == 'B':
76 back(int(op[1]))
77 if op[0] == 'D':
78 delete(int(op[1]))
79 if op[0] == 'L':
80 shiftL(int(op[1]))
81 if op[0] == 'R':
82 shiftR(int(op[1]))
83 now = nex[aga]
84
85 ans = ''
86 while (now != en):
87 ans += str(t[now])
88 now=nex[now]
89 return ans
90'''
91s = input()
92pos = int(input())
93t = int(input())
94ops = []
95for i in range(t):
96 op = list(input().split())
97 ops.append(op)
98valk = Task()
99print(valk.solver(s, pos, ops))
100'''
101'''
102whatsyourproblem
1035
1046
105L 2
106D 1
107R 4
108I abcdef
109L 3
110B 2
111'''