标签:
Description
Input
Output
Sample Input
4 3
1 2
2 3
4 3
Sample Output
1 2 4 3
---------------------------------------------------我是分割线^_^----------------------------------------------------------
这道题呢,是一道拓扑排序的入门题,其实我第一道拓扑排序是在hiho上做的,比这个要来的简单,所以
我就选这道题来记录了,这题主要是个模板,记一记花点时间理解就好,还有一点,就是题目中用到的
优先队列priority_queue,这里给出两种STL中的优先标准,小元素优先:<int, vector<int>, greater<int> >,
还有大元素优先:<int, vector<int>, greater<int> >,按照字典序大小输出时有用,记住吧。
#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<vector>
#include<queue>
using namespace std;
#define Int __int64
#define INF 0x3f3f3f3f
const int MAXN = 555;
int team[MAXN];
int head[MAXN];
int point[MAXN];
int nxt[MAXN];
int edgecnt;
bool vis[MAXN][MAXN];
int ingrade[MAXN];
void ini() {
memset(team, 0, sizeof(team));
memset(head, -1, sizeof(head));
memset(point, -1, sizeof(point));
memset(nxt, -1, sizeof(nxt));
memset(vis, 0, sizeof(vis));
memset(ingrade, 0, sizeof(ingrade));
edgecnt = 0;
}
void Add_Edge(int u, int v) {
edgecnt++;
nxt[edgecnt] = head[u];
point[edgecnt] = v;
head[u] = edgecnt;
}
int main()
{
//freopen("input.txt", "r", stdin);
int n, m;
while (scanf("%d %d", &n, &m) != EOF) {
ini();
int a, b;
int ans[MAXN] = {0};
while (m--) {
scanf("%d %d", &a, &b);
if (vis[a][b]) continue;
else vis[a][b] = true;
Add_Edge(a, b);
ingrade[b]++;
}
int k = 0;
priority_queue<int, vector<int>, greater<int> >q;
while (!q.empty()) q.pop();
for (int i = 1; i <= n; i++) {
if (ingrade[i] == 0) q.push(i);
}
while (!q.empty())