Submission #1030591

#	Time	Username	Problem	Language	Result	Execution time	Memory
1030591		sleepntsheep	Graph (BOI20_graph)	C++17	58 / 100	1022 ms	18892 KiB

Graph

#include<stdio.h>
#include<stdlib.h>
#include<vector>
#define N 100001
#define M 400001
double a(double x){return x<0?-x:x;}
int n,m,head[N],fr[M],to[M],nxt[M],col[M],ii,vis[N],aa[N],bb[N],grp[N],got[N];
double xx[N];
std::vector<int> A[N];

void link(int u,int v,int c){
    int i=++ii;
    to[i]=v;
    fr[i]=u;
    col[i]=c;
    nxt[i]=head[u];
    head[u]=i;
}

void dfs(int u,int a,int b,int cp){
    if(vis[u]){
        if(a==aa[u]&&b!=bb[u])
            exit(puts("NO")*0);
        return;
    }
    grp[u]=cp;
    A[cp].push_back(u);
    vis[u]=1,aa[u]=a,bb[u]=b;
    for(int j=head[u];j;j=nxt[j])
        dfs(to[j],-a,col[j]-b,cp);
}

int main(){
    scanf("%d%d",&n,&m);
    for(int u,v,c,i=0;i<m;++i)scanf("%d%d%d",&u,&v,&c),link(u,v,c),link(v,u,c);
    for(int i=1;i<=n;++i)
        if(!vis[i])
            dfs(i,1,0,i);

    for(int j=1;j<ii;++j){
        double a1=aa[fr[j]]+aa[to[j]],b1=bb[fr[j]]+bb[to[j]];
        int gp=grp[fr[j]];
        if(got[gp])continue;
        if(a1==0&&b1!=col[j])exit(puts("NO")*0);
        if(b1==col[j]&&a1==0)continue;
        int ok=1;
        double x = (col[j]-b1)/a1;
        for(int k=1;k<ii&&ok;++k){
            if(grp[fr[k]]!=gp)continue;
            if(aa[fr[k]]*x+bb[fr[k]]+aa[to[k]]*x+bb[to[k]] != col[k])ok=0;
        }
        if(ok)
            xx[gp]=x,got[gp]=1;
    }
    for(int i=1;i<=n;++i){
        if(got[grp[i]])continue;
        double min=1e18,argmin=424242;
        for(double f=-10000;f<=10000;f+=0.5){
            double sum=0;
            for(int j:A[grp[i]])sum+=a(aa[j]*f+bb[j]);
            if(min>sum) min=sum,argmin=f;
        }
        got[i]=1;xx[grp[i]]=argmin;
    }
    puts("YES");
    for(int i=1;i<=n;++i) printf("%.3f ",aa[i]*xx[grp[i]]+bb[i]);
}

Compilation message (stderr)

Graph.cpp: In function 'int main()':
Graph.cpp:34:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |     scanf("%d%d",&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~
Graph.cpp:35:36: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   35 |     for(int u,v,c,i=0;i<m;++i)scanf("%d%d%d",&u,&v,&c),link(u,v,c),link(v,u,c);
      |                               ~~~~~^~~~~~~~~~~~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 12 / 12
• Subtask 3: 17 / 17
• Subtask 4: 24 / 24
• Subtask 5: 0 / 42