HDU 1285 确定比赛名次 拓扑排序

思路：就是每次找一个入度为0的点。然后把这个点删掉，并将这个点连着的其他点的入度减1。

/*********************************************
Problem : HDU 1258
Author  : NMfloat
InkTime (c) NM . All Rights Reserved .
********************************************/

#include <map>
#include <set>
#include <queue>
#include <cmath>
#include <ctime>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>

#define rep(i,a,b)  for(int i = (a) ; i <= (b) ; i ++)
#define rrep(i,a,b) for(int i = (b) ; i >= (a) ; i --)
#define repE(p,u) for(Edge * p = G[u].first ; p ; p = p -> next)
#define cls(a,x)   memset(a,x,sizeof(a))
#define eps 1e-8

using namespace std;

const int MOD = 1e9+7;
const int INF = 0x3f3f3f3f;
const int MAXN = 505;
const int MAXE = 50005;

typedef long long LL;
typedef unsigned long long ULL;

int T,n,m,k;

int fx[] = {0,1,-1,0,0};
int fy[] = {0,0,0,-1,1};

int ru[505];

struct Edge { //记录边
int to;
Edge * next;
}E[MAXE],*EE;

struct Gragh { //记录图的结点
Edge * first;
}G[MAXN];

void addedge(int u,int v) { //加边,双向边
EE->to = v ; EE -> next = G[u].first ; G[u].first = EE ++;
//EE->to = u ; EE -> next = G[v].first ; G[v].first = EE ++;
}

int ans[505];

void init() {
EE = E;
cls(G,0); cls(ru,0);
}

void input() {
int u,v;
rep(i,1,m) {
scanf("%d %d",&u,&v);
addedge(u,v);
ru[v] ++;
}
}

void JIAN(int u) {
repE(p,u) {
int v = p -> to;
ru[v] --;
}
}

void solve() {
rep(i,1,n)
rep(j,1,n) {
if(ru[j] == 0) {
ru[j] = -1;
ans[i] = j;
JIAN(j);
break;
}
}
rep(i,1,n) {
printf("%d",ans[i]);
if(i == n) printf("\n");
else printf(" ");
}
}

int main(void) {
//freopen("a.in","r",stdin);
//scanf("%d",&T); while(T--) {
while(~scanf("%d %d",&n,&m)) {
//while(~scanf("%d",&n)) {
init();
input();
solve();
}
return 0;
}