Hdoj 3715-go deeper two points +2-sat judgment

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Test instructions

There is such a process:

Go (int dep, int n, int m)
Begin
Output the value of DEP.
If DEP < M and X[A[DEP]] + X[B[DEP]]! = C[DEP] Then go (dep + 1, n, m)
End

Where x[] has a value of 0 or 1...c[] with a value of 0 or 1 or 2 .... Now tell a[],b[],c[]. What is the deepest possible question of this process?

Exercises

Look at the process. In fact, there is no way to go down on the M-layer. The deeper layers are definitely not going to make it. So satisfying monotonicity ... First read in a[],b[],c[] ... Then two minutes m ... Composition.. 2-sat. Tarjan judgment ....

Program:

#include <iostream> #include <stdio.h> #include <cmath> #include <queue> #include <stack> #include <string.h> #include <map> #include <set> #include <algorithm> #define OO 1000000007#  Define MAXN 50005<<1#define Maxm 500005<<1#define ll long longusing namespace std; struct node{int y,next;} Line[maxm];int A[maxn],b[maxn],c[maxn],lnum,_next[maxn],dfn[maxn],low[maxn],tp[maxn],tpnum,dfsindex; BOOL instack[maxn];stack<int> mystack;void addline (int x,int y) {line[++lnum].next=_next[x],_next[x]=lnum,line [Lnum].y=y;}       void Tarjan (int x) {Mystack.push (x), instack[x]=true;       Dfn[x]=low[x]=++dfsindex;               for (int k=_next[x];k;k=line[k].next) {int y=line[k].y;                     if (!dfn[y]) {Tarjan (y);               Low[x]=min (Low[x],low[y]);       }else if (Instack[y]) low[x]=min (Low[x],dfn[y]); } if (Low[x]==dFn[x]) {tpnum++;                     do {x=mystack.top ();                     Mystack.pop ();                     Tp[x]=tpnum;               Instack[x]=false;       }while (Low[x]!=dfn[x]);       }}bool _2sat (int n,int M) {int i;       lnum=0;       memset (_next,0,sizeof (_next));                for (i=1;i<=m;i++) {int a=a[i],b=b[i],c=c[i];               if (!c) AddLine (a<<1,b<<1|1), AddLine (b<<1,a<<1|1); else if (c==1) {addline (a<<1,b<<1), AddLine (a<<1|1,b&lt                     ; <1|1);               AddLine (b<<1,a<<1), AddLine (b<<1|1,a<<1|1);       } else if (c==2) AddLine (a<<1|1,b<<1), AddLine (b<<1|1,a<<1);       } while (!mystack.empty ()) Mystack.pop ();       memset (dfn,0,sizeof (DFN)); memset (Instack,false,sizeof (instack));       dfsindex=tpnum=0;        For (i=0;i< (n<<1); i++) if (!dfn[i]) Tarjan (i);       for (i=0;i<n;i++) if (Tp[i<<1]==tp[i<<1|1]) return false; return true;}        int main () {int n,m,cases;       scanf ("%d", &cases);               while (cases--) {scanf ("%d%d", &n,&m);              for (int i=1;i<=m;i++) scanf ("%d%d%d", &a[i],&b[i],&c[i]);              int l=0,r=m+1,mid;                      while (r-l>1) {mid=l+r>>1;                           if (_2sat (n,mid)) L=mid;              else R=mid;       } printf ("%d\n", L);  } return 0;}