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[BestCoder Round #7] hdu 4985 Little Pony and Permutation (找循环节)
Little Pony and Permutation
Problem Description
As a unicorn, the ability of using magic is the distinguishing feature among other kind of pony. Being familiar with composition and decomposition is the fundamental course for a young unicorn. Twilight Sparkle is interested in the decomposition of permutations. A permutation of a set S = {1, 2, ..., n} is a bijection from S to itself. In the great magician —— Cauchy‘s two-line notation, one lists the elements of set S in the first row, and then for each element, writes its image under the permutation below it in the second row. For instance, a permutation of set {1, 2, 3, 4, 5} σ can be written as:
Here σ(1) = 2, σ(2) = 5, σ(3) = 4, σ(4) = 3, and σ(5) = 1.
Twilight Sparkle is going to decompose the permutation into some disjoint cycles. For instance, the above permutation can be rewritten as:
Help Twilight Sparkle find the lexicographic smallest solution. (Only considering numbers).
Input
Input contains multiple test cases (less than 10). For each test case, the first line contains one number n (1<=n<=10^5). The second line contains n numbers which the i-th of them(start from 1) is σ(i).
Output
For each case, output the corresponding result.
Sample Input
5 2 5 4 3 1 3 1 2 3
Sample Output
(1 2 5)(3 4) (1)(2)(3)
Source
BestCoder Round #7
找循环节,用while循环就可以了,注意输出格式。
代码:
#include <iostream> #include <stdio.h> #include <string.h> using namespace std; const int maxn=100010; int num[maxn]; bool vis[maxn]; int n; void getCircle() { memset(vis,0,sizeof(vis)); int t; bool ok=0; for(int i=1;i<=n;i++) { int temp=i; if(!vis[temp]) printf("("); while(!vis[temp]) { t=temp; vis[temp]=true; temp=num[temp]; if(!vis[temp]) printf("%d ",t); else { printf("%d",t); ok=1; } } if(ok) { printf(")"); ok=0; } } printf("\n"); } int main() { while(scanf("%d",&n)!=EOF) { for(int i=1;i<=n;i++) scanf("%d",&num[i]); getCircle(); } return 0; }
[BestCoder Round #7] hdu 4985 Little Pony and Permutation (找循环节)
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