14：Labeling Balls

Description

Windy hasNballs of distinct weights from 1 unit toNunits. Now he tries to label them with 1 toNin such a way that:

1. No two balls sharethe same label.

2. The labelingsatisfies several constrains like "The ball labeled withais lighter than the one labeled withb".

Can you help windy tofind a solution?

Input

The first line ofinput is the number of test case. The first line of each test casecontains two integers,N(1 ≤N ≤ 200) andM (0 ≤ M≤ 40,000). The nextMline each contain two integersaandb indicating theball labeled withamust be lighter than the one labeled withb.(1 ≤a, b ≤N)There is a blank line before each test case.

Output

For each test caseoutput on a single line the balls' weights from label 1 to labelN.If several solutions exist, you should output the one with thesmallest weight for label 1, then with the smallest weight for label2, then with the smallest weight for label 3 and so on... If nosolution exists, output -1 instead.

SampleInput

5

4 0

4 1

1 1

4 2

1 2

2 1

4 1

2 1

4 1

3 2

SampleOutput

1 2 3 4

-1

-1

2 1 3 4

1 3 2 4

算法思路：拓扑排序，先将图输入到矩阵中，对于每个点来说，每行的和表示出度，每列的和表示入度。ID从小到大进入队，依次检查每个顶点，如果入度为0，删除该点，并在下次计算入度时，不再加上该行的值。如果没有入度为0的点，程序就结束。

package OJ;import java.util.*;public class P14_temp {public static void main(String[] args) {class Vertex {int export;int num;public Vertex(int num){export = 0;this.num = num;}public Vertex(int num, int export){this.export = export;this.num = num;}public void addEx(){export++;}public void removeEx(int ex){export = export -ex;}public int getNum(){return num;}public int getEx(){return export;}}Scanner in = new Scanner(System.in);int cases = in.nextInt();ArrayList<ArrayList<Integer>> results = new ArrayList<ArrayList<Integer>>();while(cases > 0){int arraysize = in.nextInt(); //二维数组的宽度int[][] graph = new int[arraysize][arraysize];ArrayList<Vertex> vertexs = new ArrayList<Vertex>();//顶点集合for(int k=0; k<arraysize; k++)vertexs.add(new Vertex(k+1));int inputrows = in.nextInt();while(inputrows > 0){int i = in.nextInt()-1;int j = in.nextInt()-1;graph[i][j] = 1;vertexs.get(i).addEx();inputrows--;}ArrayList<Integer> result = new ArrayList<Integer>();for(int t=vertexs.size()-1; t>-1;){if(vertexs.get(t).getEx() == 0){result.add(vertexs.get(t).getNum());for(int m=0; m<arraysize; m++){if(graph[m][t] == 1){graph[m][t] = 0;vertexs.get(m).removeEx(1);}}vertexs.remove(t);t = vertexs.size()-1;continue;}t--;}if(vertexs.size() != 0){result.clear();result.add(-1);results.add(result);}elseresults.add(result);cases--;}for(int n=0; n<results.size(); n++){for(int r=results.get(n).size()-1; r >-1; r--){if(r == 0){System.out.println(results.get(n).get(r));}elseSystem.out.print(results.get(n).get(r) + " ");}}}}