拓扑排序

//拓扑排序
class TopologicalSort{
    int[][] graph;
    int[] list;
    void input(int[][] graph){
        this.graph=graph;
        list=new int[graph.length];
        calculate();
    }
    void calculate(){
        Stack stack=new Stack();
        for(int i=0; i<graph.length; i++){
            if(graph[i][0]==0){
                stack.push(i);
            }
        }
        int i=0;
        while(stack.empty()!=true){
            list[i]=(Integer)stack.pop();
            for(int j=1; j<graph[list[i]].length; j++){
                int k=graph[list[i]][j];
                if((--graph[k][0])==0){
                    stack.push(k);
                }
            }
            i++;
        }
        if(i<graph.length){
            System.out.println("存在环，不可排序！");
            System.exit(0);
        }
    }
    int[] getList(){
        return list;
    }
}
public static void main(String[] args){
    int[][] graph={{0,1,2,3,},{2,},{1,1,4,},{2,4,},{3,},{0,3,4,},};
    int[] list=new int[graph.length];;
    TopologicalSort topologicalSort=new TopologicalSort();
    topologicalSort.input(graph);
    list=topologicalSort.getList();
    for(int l : list){
        System.out.print(l+" ");
    }
}