Submission #2875531

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Source Code Expand

#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;

#define MAXN 100000
#define INF (1ll<<50)
int N,M;
struct Edge{
    int v,w;
    Edge(){}
    Edge(int a,int b){
        v=a,w=b;
    }
};
vector<Edge> G[MAXN+5];
long long Lim[2][MAXN+5];
//S1 < Lim[0][i]
//S1 > Lim[1][i]

void dfs(int u,int f,int Sign,long long Sum){
    for(int i=0;i<int(G[u].size());i++){
        int v=G[u][i].v,w=G[u][i].w;
        if(v!=f){
            int id=Sign==1?0:1;
            long long tmp=Sum+Sign*w;
            if(Lim[id][v]!=INF){
                if(Lim[id][v]!=tmp){
                    puts("0");
                    exit(0);
                }
                else
                    continue;
            }
            Lim[id][v]=tmp;
            dfs(v,u,-Sign,tmp);
        }
    }
}

int main(){
    scanf("%d%d",&N,&M);
    for(int i=1;i<=M;i++){
        int u,v,w;
        scanf("%d%d%d",&u,&v,&w);
        G[u].push_back(Edge(v,w));
        G[v].push_back(Edge(u,w));
    }
    fill(Lim[0]+1,Lim[0]+N+1,INF);
    fill(Lim[1]+1,Lim[1]+N+1,INF);
    dfs(1,-1,1,0ll);
    long long Left=0,Right=INF;
    for(int i=2;i<=N;i++){
        if(Lim[1][i]!=INF)
            Left=max(Left,Lim[1][i]);
        if(Lim[0][i]!=INF)
            Right=min(Right,Lim[0][i]);
    }
    long long Sure=-1,flag=INF;
    for(int i=2;i<=N;i++)
        if(Lim[0][i]!=INF&&Lim[1][i]!=INF){
            long long k=Lim[0][i]+Lim[1][i];
            if(k%2||k/2<0) flag=0;
            if(Sure==-1) Sure=k/2;
            else if(Sure!=k) flag=0;
        }
    if(Sure!=-1){
        if(Left<Sure&&Sure<Right) puts("1");
        else puts("0");
        return 0;
    }
    printf("%lld",min(flag,max(Right-Left-1,0ll)));
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:42:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&N,&M);
                        ^
./Main.cpp:45:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&u,&v,&w);
                                 ^

Judge Result