UVALive 5010 Go Deeper 2sat

二分答案，2sat判定。

//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<iostream>
#include<sstream>
#include<cmath>
#include<climits>
#include<string>
#include<map>
#include<queue>
#include<vector>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
#define pb(a) push(a)
#define INF 0x1f1f1f1f
#define lson idx<<1,l,mid
#define rson idx<<1|1,mid+1,r
#define PI  3.1415926535898
template<class T> T min(const T& a,const T& b,const T& c) {
    return min(min(a,b),min(a,c));
}
template<class T> T max(const T& a,const T& b,const T& c) {
    return max(max(a,b),max(a,c));
}
void debug() {
#ifdef ONLINE_JUDGE
#else

    freopen("in.txt","r",stdin);
    //freopen("d:\\out1.txt","w",stdout);
#endif
}
int getch() {
    int ch;
    while((ch=getchar())!=EOF) {
        if(ch!=' '&&ch!='\n')return ch;
    }
    return EOF;
}

const int maxn=;
struct TwoSat
{
    int n;
    vector<int> g[maxn*];
    bool mark[maxn*];
    int s[maxn*],c;
    bool dfs(int x)
    {
        if(mark[x^])return false;
        if(mark[x])return true;
        mark[x]=true;
        s[c++]=x;
        for(int i=;i<g[x].size();i++)
        {
            if(!dfs(g[x][i]))return false;
        }
        return true;
    }
    void init(int n)
    {
        this->n=n;
        for(int i=;i<n*;i++)
            g[i].clear();
        memset(mark,,sizeof(mark));
    }
    void add_clause(int x,int xval,int y,int yval)
    {
        x=x*+xval;
        y=y*+yval;
        g[x].push_back(y^);
        g[y].push_back(x^);
    }
    bool solve()
    {
        for(int i=;i<n*;i+=)
        {
            if(!mark[i]&&!mark[i+])
            {
                c=;
                if(!dfs(i))
                {
                    while(c>)mark[s[--c]]=;
                    if(!dfs(i+))return false;
                }
            }
        }
        return true;
    }
};

TwoSat solver;

const int maxm=;
int a[maxm],b[maxm],c[maxm];
int n,m;
int check(int k)
{
    solver.init(n);
    for(int i=;i<k;i++)
    {
        if(c[i]==)
        {
            int x=a[i],y=b[i];
            solver.add_clause(x,,y,);
        }
        if(c[i]==)
        {
            int x=a[i],y=b[i];
            solver.add_clause(x,,y,);
        }
        if(c[i]==)
        {
            int x=a[i],y=b[i];
            solver.add_clause(x,,y,);
            solver.add_clause(x,,y,);
        }
    }
    return solver.solve();
}
int main()
{
    int t;
    scanf("%d",&t);
    for(int ca=;ca<=t;ca++)
    {
        scanf("%d%d",&n,&m);
        for(int i=;i<m;i++)
            scanf("%d%d%d",&a[i],&b[i],&c[i]);
        int l=,r=m+;
        while(l<r)
        {
            int mid=(r+l)>>;
            if(check(mid))
                l=mid+;
            else r=mid;
        }
        printf("%d\n",l-);
    }
    return ;
}