POJ 3687 Labeling Balls

大意略。

思路：把指向關係變一下，即A->B代表A重量一定比B重要要大。然後拓撲時，從編號最大的開始尋找即可。

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>
#include <cstring>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <map>
using namespace std;

const int maxn = 210;
const int maxm = 210*210;

const int INF = 0x3f3f3f3f;

int cnt;
int first[maxn];

int topo[maxn];
int ind[maxn];

struct Edge
{
	int u, v;
	int next;
}edge[maxm];

void init()
{
	cnt = 0;
	memset(first, -1, sizeof(first));
	memset(ind, 0, sizeof(ind));
}

void read_graph(int u, int v)
{
    edge[cnt].u = u, edge[cnt].v = v;
    edge[cnt].next = first[u], first[u] = cnt++;
}

inline void readint(int &x)
{
    char c = getchar();
    while(!isdigit(c)) c = getchar();
    
    x = 0;
    while(isdigit(c))
    {
        x = x*10 + c-'0';
        c = getchar();
    }
}

inline void writeint(int x)
{
    if(x > 9) writeint(x/10);
    putchar(x%10+'0');
}

int n, m;

void read_case()
{
	init();
	readint(n), readint(m);
	
	for(int i = 0; i < m; i++)
	{
		int u, v;
		readint(u), readint(v);
		read_graph(v, u);
		ind[u]++;
	}
}

int toposort()
{
	for(int i = 1; i <= n; i++)
	{
		int c = 0, u;
		for(int j = n; j >= 1; j--) if(!ind[j]) { c++; u = j; break; }
		
		if(c == 0) return -1;
		topo[i] = u;
		ind[u] = -1;
		
		for(int e = first[u]; e != -1; e = edge[e].next)
		{
			int v = edge[e].v;
			ind[v]--;
		}
	}
	return 1;
}

int weight[maxn];

void solve()
{
	read_case();
	int ans = toposort();
	if(ans == -1) { printf("-1\n"); return; }
	
	for(int i = 1; i <= n; i++)
	{
		weight[topo[i]] = n-i+1;
	}
	
	int first = 1;
	
	for(int i = 1; i <= n; i++)
	{
		if(first) printf("%d", weight[i]), first = 0;
		else printf(" %d", weight[i]);
	}
	printf("\n");
}

int main()
{
	int T;
	readint(T);
	while(T--)
	{
		solve();
	}
	return 0;
}