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!='
')return ch;
    }
    return EOF;
}

const int maxn=205;
struct TwoSat
{
    int n;
    vector<int> g[maxn*2];
    bool mark[maxn*2];
    int s[maxn*2],c;
    bool dfs(int x)
    {
        if(mark[x^1])return false;
        if(mark[x])return true;
        mark[x]=true;
        s[c++]=x;
        for(int i=0;i<g[x].size();i++)
        {
            if(!dfs(g[x][i]))return false;
        }
        return true;
    }
    void init(int n)
    {
        this->n=n;
        for(int i=0;i<n*2;i++)
            g[i].clear();
        memset(mark,0,sizeof(mark));
    }
    void add_clause(int x,int xval,int y,int yval)
    {
        x=x*2+xval;
        y=y*2+yval;
        g[x].push_back(y^1);
        g[y].push_back(x^1);
    }
    bool solve()
    {
        for(int i=0;i<n*2;i+=2)
        {
            if(!mark[i]&&!mark[i+1])
            {
                c=0;
                if(!dfs(i))
                {
                    while(c>0)mark[s[--c]]=0;
                    if(!dfs(i+1))return false;
                }
            }
        }
        return true;
    }
};

TwoSat solver;

const int maxm=10005;
int a[maxm],b[maxm],c[maxm];
int n,m;
int check(int k)
{
    solver.init(n);
    for(int i=0;i<k;i++)
    {
        if(c[i]==0)
        {
            int x=a[i],y=b[i];
            solver.add_clause(x,0,y,0);
        }
        if(c[i]==2)
        {
            int x=a[i],y=b[i];
            solver.add_clause(x,1,y,1);
        }
        if(c[i]==1)
        {
            int x=a[i],y=b[i];
            solver.add_clause(x,0,y,1);
            solver.add_clause(x,1,y,0);
        }
    }
    return solver.solve();
}
int main()
{
    int t;
    scanf("%d",&t);
    for(int ca=1;ca<=t;ca++)
    {
        scanf("%d%d",&n,&m);
        for(int i=0;i<m;i++)
            scanf("%d%d%d",&a[i],&b[i],&c[i]);
        int l=0,r=m+1;
        while(l<r)
        {
            int mid=(r+l)>>1;
            if(check(mid))
                l=mid+1;
            else r=mid;
        }
        printf("%d
",l-1);
    }
    return 0;
}