Dancing Link---Template title HUST 1017-exact cover

1017-exact Cover problem ' s Link: http://acm.hust.edu.cn/problem/show/1017

Mean:

Slightly

Analyse:

A

Time Complexity:o (n)

Source Code:

#include <stdio.h>#include<string.h>#include<iostream>#include<algorithm>#include<vector>#include<queue>#include<Set>#include<map>#include<string>#include<math.h>#include<stdlib.h>#include<time.h>using namespacestd;Const intMaxnode =100010;Const intMAXN =1010;structdlx{intn,m,size; intU[maxnode],d[maxnode],r[maxnode],l[maxnode],row[maxnode],col[maxnode]; intH[MAXN], S[MAXN];//H[i]---the first row i is 1 index s[i]---Number i column 1    intANSD, ANS[MAXN]; voidInitint_n,int_m) {N=_n; M=_m;  for(inti =0; I <= m;i++)//Initialize the first row (c[in the figure]){S[i]=0;//number of 1 in column IU[i] = D[i] =i; L[i]= I1; R[i]= i+1; } R[m]=0; l[0] = m;//the last of the first line points to the first line (looping)size = m;//from M onwards, it's all common knots .         for(inti =1; I <= n;i++) H[i]= -1;//H[i]---The first 1 node number on line I    }    voidLink (intRintC//ranks    {        //D[c]---The next pointer in column Cs[col[++size]=c]++;//Normal node subscript + + The number of columns in the size node is the number of nodes in C column C + +Row[size] = r;//the number of rows for the first size node is R .D[size] = D[c];//The next pointer to the size node is: The next pointer to column No. 0, Row CU[size] = c;//The pointer on the first size node is: column No. 0 (only if the input row is incremented)U[D[C]] = size;//The pointer on column C of line No. 0 is: sizeD[C] = size;//The next pointer to the size above is: size (a bit around)        if(H[r] <0) H[r] = l[size] = r[size] = size;//the line has only one node around the pointer itself pointing itself        Else{R[size]= R[h[r]];//LoopingL[r[h[r]] =size; L[size]=H[r]; R[H[R]]=size; }    }    voidRemoveintc) {L[r[c]]= L[c]; R[L[C]] =R[c];  for(inti = d[c];i! = C;i =D[i]) for(intj = r[i];j! = I;j =R[j]) {U[d[j]]=U[j]; D[U[J]]=D[j]; --S[col[j]]; }    }    voidResumeintc) { for(inti = u[c];i! = C;i =U[i]) for(intj = l[i];j! = I;j =L[j])++s[col[u[d[j]]=d[u[j]]=J]]; L[R[C]]= R[l[c]] =C; }    //d is recursive depth    BOOLDance (intd) {if(r[0] ==0)//R[0]==r[m]//There's no knot in line No. 0 .{ANSD=D; return true; }        intc = r[0];  for(inti = r[0];i! =0; i = R[i])//go right (Find a column with the fewest nodes)            if(S[i] < s[c])//Column I node number < column C node numberc =i; Remove (c); //Remove C node         for(inti = d[c];i! = C;i = D[i])//find the smallest of these columns and go down.{Ans[d]=Row[i];  for(intj = R[i]; J! = I;j = R[j]) remove (col[j]);//remove the column corresponding to the row            if(Dance (d+1))return true;//recursive next layer             for(intj = L[i]; J! = I;j = L[j]) resume (col[j]);//Backwards Connection} resume (c); return false; }};D lx G;intMain () {//freopen ("In.txt", "R", stdin); //freopen ("OUT.txt", "w", stdout);    intn,m;  while(SCANF ("%d%d", &n,&m) = =2) {g.init (n,m);  for(inti =1; I <= n;i++)//Line        {            intnum,j; scanf ("%d",&num);  while(num--) {scanf ("%d", &j);//columnG.link (I,J); }        }        if(!g.dance (0)) printf ("no\n"); Else{printf ("%d", G.ANSD);  for(inti =0; I < g.ansd;i++) printf ("%d", G.ans[i]); printf ("\ n"); }    }    return 0;}

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Dancing Link---Template title HUST 1017-exact cover