int* indegree = (int*)malloc(sizeof(int) * G.vexnum);
//對(duì)單個(gè)節(jié)點(diǎn)p求入度
void CountIndegree(AdjList g, int* indegree, ArcNode* p) {
	while (p != NULL) {
		indegree[p->adjvex]++;
		p = p->nextarc;
	}
	return;
}

bool TopoSort(AdjList g, int* indegree) {
	//先清空申請(qǐng)的indegree數(shù)組，或者也可以在初始化時(shí)采用calloc，就不用在這里置為0了
	for (int i = 0; i < g.vexnum; i++) {
		indegree[i] = 0;
	}
	//遍歷邊表中的每一個(gè)頂點(diǎn)，用CountIndegree()遍歷單個(gè)節(jié)點(diǎn)
	for (int i = 0; i < g.vexnum; i++) {
		ArcNode* p = g.vertexlist[i].firstarc;
		CountIndegree(g, indegree, p);
	}
	stack<int>S;
	//如果該頂點(diǎn)的入度為0，則入棧。
	for (int i = 0; i < g.vexnum; i++) {
		if (indegree[i] == 0) {
			S.push(i);
		}
	}
	//count用來表示已經(jīng)輸出的節(jié)點(diǎn)個(gè)數(shù)
	//如果所有的頂點(diǎn)被輸出，則count==g.vexnum，無回路，反之count<g.vexnum,則是有回路。
	int count = 0;
	while (!S.empty()) {
		int top = S.top();
		printf("%c ", g.vertexlist[top].data);
		S.pop();
		count++;
		ArcNode* p = g.vertexlist[top].firstarc;
		for (p; p != NULL; p = p->nextarc) {
			int i = p->adjvex;
			if (--indegree[i] == 0) {
				S.push(i);
			}
		}
	}
	if (count == g.vexnum) {
		return true;
	}
	return false;
}