Ordering Tasks

https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=1246

C++版本一

题解：拓扑排序

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=200+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,r,u,v;
int ans[N],cnt,flag,temp,sum;
int in[N];
int mp[N][N];
char str;
struct node{};
void dfs(){
    queue<int>q;
    for(int i=1;i<=n;i++)
        if(in[i]==0)
            q.push(i);
    while(!q.empty()){
        int tmp=q.front();
        q.pop();
        ans[++cnt]=tmp;
        for(int i=1;i<=n;i++){
            if(mp[tmp][i]){
                in[i]--;
                if(in[i]==0){
                    q.push(i);
                }
            }
        }
    }
}
void init(){
    memset(in,0,sizeof(in));
    memset(mp,0,sizeof(mp));
    cnt=0;
}
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    while(~scanf("%d%d",&n,&m)&&(m+n)){
        init();
        for(int i=1;i<=m;i++){
            scanf("%d%d",&u,&v);
            mp[u][v]=1;
            in[v]++;
        }
        dfs();
        for(int i=1;i<=n;i++)
            printf("%d%c",ans[i]," \n"[i==n]);
    }

#ifdef DEBUG
	printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}

C++版本二

DFS

#include <iostream>
#include <cstdio>
#include <queue>
#include <map>
#include <algorithm>
#include <cstring>
using namespace std;
///拓扑排序学习题  递归形式dfs 选中一个未排序的元素进行dfs把在他之后的装进ans（倒着装）并标记。

int n,m,a,b,ans[101],mp[101][101]={0},vis[101]={0},k;
bool dfs(int last)
{
    vis[last]=-1;
    for(int i=1;i<=n;i++)
        if(mp[last][i])
        {
            if(vis[i]==0)dfs(i);
            else if(vis[i]==-1)return false;//形成了回路 无法继续排序 -1表示i比last先入栈。
        }
    ans[--k]=last;
    vis[last]=1;
    return true;
}
int main()
{
    while(scanf("%d%d",&n,&m))
    {
        if(!(n+m))break;
        k=n;
        memset(vis,0,sizeof(vis));
        memset(mp,0,sizeof(mp));
        for(int i=0;i<m;i++)
        {
            scanf("%d%d",&a,&b);
            mp[a][b]=1;
        }
        for(int i=1;i<=n;i++)
        {
            if(!vis[i])
            {
                if(!dfs(i))break;
            }
        }
        for(int i=k;i<n;i++)
            printf("%d ",ans[i]);
        putchar('\n');
    }
}

C++版本三

#include <cstdio>
#include <cstring>
const int maxn = 101;
 
int g[maxn][maxn], id[maxn], q[maxn];
 
int main() {
//	freopen("in", "r", stdin);
	int n, m, a, b, tmp;
	int front, tail;
	while (scanf("%d%d", &n, &m)) {
		if (n == 0 && m == 0)
			break;
		memset(g, 0, sizeof(g));
		memset(id, 0, sizeof(id));
		front = tail = 0;
		for (int i = 0; i < m; i++)  {
			scanf("%d%d", &a, &b);
			g[a][b] = 1;
			id[b]++;
		}
		for (int i = 1; i <= n; i++)
			if (id[i] == 0)
				q[tail++] = i;
		while (tail != front) {
			tmp = q[front++];
			if (front == 1)
				printf("%d", tmp);
			else
				printf(" %d", tmp);
			for (int i = 1; i <= n; i++)
				if (g[tmp][i] != 0)
					if (--id[i] == 0)
						q[tail++] = i;
		}//while
		printf("\n");
	}//while 
	return 0;
}

C++版本四

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
#define endl "\n"
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=200+10;
const int M=100000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
int t,n,m,k,p,l,r,u,v;
int ans[N],cnt,flag,temp,sum;
int vis[N];
int mp[N][N];
char str;
struct node{};
void dfs(int u){
    vis[u]=-1;
    for(int i=1;i<=n;i++){
        if(mp[u][i]){
            if(vis[i]==0)
                dfs(i);
            else if(vis[i]==-1)
                return;
        }
    }
    ans[cnt--]=u;
    vis[u]=1;
}
void init(){
    memset(vis,0,sizeof(vis));
    memset(mp,0,sizeof(mp));
    cnt=n;
}
int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    //ios::sync_with_stdio(false);
    //cin.tie(0);
    //cout.tie(0);
    //scanf("%d",&t);
    while(~scanf("%d%d",&n,&m)&&(m+n)){
        init();
        for(int i=1;i<=m;i++){
            scanf("%d%d",&u,&v);
            mp[u][v]=1;
        }
        for(int i=1;i<=n;i++){
            if(!vis[i]){
                dfs(i);
            }
        }
        for(int i=1;i<=n;i++)
            printf("%d%c",ans[i]," \n"[i==n]);
    }

#ifdef DEBUG
	printf("Time cost : %lf s\n",(double)clock()/CLOCKS_PER_SEC);
#endif
    //cout << "Hello world!" << endl;
    return 0;
}