求助！orz无法解释！灵异事件！

hgfs @ 2024-07-18 10:15:35

#include<bits/stdc++.h>
using namespace std;

int const N=5003,M=200003;
int g[N][N],dis[N],n,m,su;
bool st[N];

int find(){
    int an,in=0x3f3f3f3f;
    for(int i=1;i<=n;i++){
        if(dis[i]<in && !st[i]){
            in=dis[i];
            an=i;
        }
    }
    st[an]++;
    return an;
}
/*-------法二
    int t=-1;
    for(int j=1;j<=n;j++){
        if(!st[j] && (t==-1 || dis[j]<dis[t]))
        t=j;
    }
    st[t]=1;
*/

int main(){
    cin>>n>>m;
    memset(g,0x3f,sizeof(g));
    memset(dis,0x3f,sizeof(dis));
    for(int i=1;i<=m;i++){
        int x,y,z;
        cin>>x>>y>>z;
        if(x==y) continue;
        g[x][y]=min(g[x][y],z);//防止重边。
        g[y][x]=min(g[y][x],z);
    }
    dis[1]=0;//编号1的点距离为0.
    for(int i=1;i<=n;i++){
        int x=find();
        for(int j=1;j<=n;j++) dis[j]=min(dis[j],min(g[j][x],g[x][j]));//枚举其他边。
        cout<<x<<' '<<dis[x]<<endl;
        if(i!=1 && dis[x]==0x3f3f3f3f){
            cout<<"orz";//无法到达，
            return 0;
        }
        su+=dis[x];
    }
    cout<<su;
    return 0;
}
/*

5 6
1 2 3
2 3 4
3 1 4
4 5 6
5 4 6
1 3 5

*/

by Kavin_0409 @ 2024-07-18 10:27:46

6

by Kavin_0409 @ 2024-07-18 10:28:16

确实奇葩

by nr0728 @ 2024-07-18 10:31:36

@hgfs 你把 cout 改成 cerr 试试

上次就有道题我代码有 ub，加上 cout 就对了，然后把 cout 改成 cerr，不开 O2 交就能 A

by nr0728 @ 2024-07-18 10:32:57

@hgfs 你代码不是 CE 了吗，是不是直接执行编译好的源文件没注意到 CE

/tmp/compiler_2dz3pkft/src:16:14: 错误：use of an operand of type ‘bool’ in ‘operator++’ is forbidden in C++17

by hgfs @ 2024-07-18 11:07:49

@nr0728 感谢感谢！关了o2就过了。

好像没有CE呀~~

by zhaoyonghao @ 2024-08-01 08:14:35

我喜欢链式前向星

#include <bits/stdc++.h>
using namespace std;

int m, n, head[5005], cnt, dis[5005];
bool vis[5005];
struct node{
    int to, w, next;
}edge[400005];

void add(int u, int v, int w) 
{
    edge[++cnt] = {v, w, head[u]};
    head[u] = cnt;
}

int main()
{
    memset(head, -1, sizeof head); 
    memset(dis, 0x3f, sizeof dis);
    cin >> m >> n;
    for (int i = 1; i <= n; i++)
    {
        int u, v, w;
        cin >> u >> v >> w;
        add(u, v, w);
        add(v, u, w);
    }
    dis[1] = 0;
    int ans = 0;
    for (int i = 1; i <= m; i++)
    {
        int x = 0;
        for (int j = 1; j <= m; j++)
            if (dis[j] < dis[x] && vis[j] == 0) x = j;
        ans += dis[x];
        vis[x] = 1;
        for (int j = head[x]; j != -1; j = edge[j].next)
            if (vis[edge[j].to] == 0) dis[edge[j].to] = min(dis[edge[j].to], edge[j].w);
    }
    for (int i = 1; i <= m; i++)
        if (!vis[i])
        {
            cout << "orz\n";
            return 0;
        }
    cout << ans << "\n";
    return 0;
}