洛谷P3014 [USACO11FEB]牛线Cow Line

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关于康托展开 与 康托逆展开

 1 #include <bits/stdc++.h>
 2 #define For(i, j, k) for(int i=j; i<=k; i++)
 3 #define Dow(i, j, k) for(int i=j; i>=k; i--)
 4 #define LL long long
 5 using namespace std;
 6 inline LL read() {
 7     LL x = 0, f = 1;
 8     char ch = getchar();
 9     while(ch<‘0‘||ch>‘9‘) { if(ch==‘-‘) f = -1; ch = getchar(); }
10     while(ch>=‘0‘&&ch<=‘9‘) { x = x*10+ch-48; ch = getchar(); }
11     return x * f;
12 }
13 void write(LL x) {
14     if(x<0) putchar(‘-‘), x = -x;
15     if(x>9) write(x/10);
16     putchar(x%10+48);
17 }
18 inline void writeln(LL x) { write(x); putchar(‘\n‘); }
19
20 const int N = 30;
21 int n,Ques;
22 LL Fact[N];
23 int vis[N];
24
25 inline void calc(int n) {
26     Fact[0]=1;
27     For(i, 1, n) Fact[i]=Fact[i-1]*i;
28 }
29
30 inline int getpre(int n, int x) {
31     vis[x] = 1;
32     int res = 0;
33     For(i, 1, x-1)
34         if(!vis[i]) ++res;
35     return res;
36 }
37
38 inline void getprint(int n, LL x) {
39     int pos = 0;
40     For(i, 1, x+1) {
41         ++pos;
42         while(vis[pos] && pos<=n) ++pos;
43     }
44     vis[pos] = 1;
45     write(pos); putchar(‘ ‘);
46 }
47
48 int main() {
49     n = read(); Ques = read();
50     calc(n);
51     while(Ques--) {
52         char s[10];
53         scanf("%s",s+1);
54         if(s[1]==‘Q‘) {
55             LL ans = 0;
56             For(i, 0, n) vis[i] = 0;
57             Dow(i, n, 1) {
58                 int x = read();
59                 ans += getpre(n, x)*Fact[i-1];   //  这里可以用树状数组来优化
60             }
61             writeln(ans+1);
62         }
63         else {
64             For(i, 0, n) vis[i] = 0;
65             LL x = read(); x--;
66             Dow(i, n, 1) {
67                 getprint(n, x/Fact[i-1]);
68                 x %= Fact[i-1];
69             }
70             puts("");
71         }
72     }
73     return 0;
74 }

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原文地址：https://www.cnblogs.com/third2333/p/8457949.html