拓扑排序

看了参加ACM的人写的程序，只能说他们成魔了啊....空间太节省了....

#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <algorithm>
#include <map>
#include <stack>
using namespace std;

void findOrder(int cnt, map<int, int> depNum, map<int, map<int, bool> > dep) {
//拓扑排序
    for (int i = 0; i < cnt; ++i) {
        int choice = 2550;
        for (int j = 0; j < cnt; ++j) {
            if (depNum[j] == 0) {
                choice = min(choice, j);
                break;
            }
        }

        if (choice == 2550) {
            cout << "circle!";
        }
        depNum[choice] = -1;
        for (int j = 0; j < cnt; ++j) {
            if (dep[choice][j]) {
                depNum[j]--;
            }
        }
        cout << choice << " ";
    }
}


/*==================================================*\
 |  拓扑排序
 | INIT:edge[][] 置为图的邻接矩阵;count[0…i…n-1]: 顶点i 的入度.
 | 和TopoOrder实现的原理是一样的，只是没有用count。
 \*==================================================*/
void TopoOrder_easy(int n, map<int, int> count, map<int, map<int, bool> > edge) {
    int i, top = -1;
    stack<int> sh;
    for (i = 0; i < n; ++i)
        if (count[i] == 0) { //  下标模拟堆栈
            sh.push(i);
            top = i;
        }

    for (i = 0; i < n; ++i)
        if (sh.empty()) {
            cout << " circle\n";
            return;
        } else {

            int j = sh.top();
            sh.pop();
            cout << j << " ";
            for (int k = 0; k < n; ++k)
                if (edge[j][k] && (--count[k]) == 0) {
                    sh.push(k);
                }

        }
}



/*==================================================*\
 |  拓扑排序
 | INIT:edge[][] 置为图的邻接矩阵;count[0…i…n-1]: 顶点i 的入度.
 \*==================================================*/
void TopoOrder(int n, map<int, int> count, map<int, map<int, bool> > edge) {
    int i, top = -1;
    for (i = 0; i < n; ++i)
        if (count[i] == 0) { //  下标模拟堆栈
            count[i] = top;
            top = i;
        }

    for (i = 0; i < n; ++i)
        if (top == -1) {
            cout << " circle\n";
            return;
        } else {
            int j = top;
            top = count[top];
            cout << j << " ";
            for (int k = 0; k < n; ++k)
                if (edge[j][k] && (--count[k]) == 0) {
                    count[k] = top;
                    top = k;
                }
        }
}

int main() {
    map<int, int> count;
    map<int, map<int, bool> > edge;

    for (int i = 0; i < 4; i++)
        for (int j = 0; j < 4; j++)
            edge[i][j] = 0;
    edge[3][1] = edge[3][0] = 1;

    for (int i = 0; i < 4; i++)
        for (int j = 0; j < 4; j++) {
            if (edge[i][j]) {
                count[j]++;
            }
        }
    TopoOrder_easy(4, count, edge);
    cout<<endl;
    TopoOrder(4, count, edge);
    cout << endl;
    findOrder(4, count, edge);
    return 0;
}