C++ 使用舞蹈链接的精确封面
在经历了这些之后,我试图实现舞蹈链接来解决确切的封面问题,下面是从中提取并修改的代码(这是列-行结构,我需要行-列结构)。它工作得很好,只是在C++ 使用舞蹈链接的精确封面,c++,algorithm,knuth,C++,Algorithm,Knuth,在经历了这些之后,我试图实现舞蹈链接来解决确切的封面问题,下面是从中提取并修改的代码(这是列-行结构,我需要行-列结构)。它工作得很好,只是在搜索函数中,它从未到达成功的终止块。我尝试跟踪,发现 RowNode = Column->Down ; RowNode!=Column ; RowNode = RowNode->Down 是谁造成的。示例:对于以下矩阵 1 2 3 4 1 1 x x x 1 1 x x x 1 1 我的代码未能覆盖标题为4的最后一列 我怎样才能克服这个问题
搜索
函数中,它从未到达成功的终止块。我尝试跟踪,发现
RowNode = Column->Down ; RowNode!=Column ; RowNode = RowNode->Down
是谁造成的。示例:对于以下矩阵
1 2 3 4
1 1 x x
x 1 1 x
x x 1 1
我的代码未能覆盖标题为4的最后一列
我怎样才能克服这个问题?这是完整的代码
#include <iostream>
#include <vector>
#include <cstdio>
#include <stdbool.h>
#define MAX_ROW 50L
#define MAX_COL 100L
using namespace std;
struct str_node {
struct str_node * Header;
struct str_node * Left;
struct str_node * Right;
struct str_node * Up;
struct str_node * Down;
int HeaderID,RowIndex,ColIndex;
};
int nCol;
int nRow;
struct str_node Matrix[MAX_ROW][MAX_COL];
vector<struct str_node*>ResultRow;
struct str_node Root;
struct str_node *RootNode = &Root;
bool Data[MAX_ROW][MAX_COL];
int maxResult;
//functions to get the neighbours (are circular)
inline int dataLeft(int i) { return (i-1 < 0) ? nCol-1 : i-1 ; }
inline int dataRight(int i) { return (i+1) % nCol ; }
inline int dataUp(int i) { return (i-1 < 0) ? nRow-1 : i-1 ; }
inline int dataDown(int i) { return (i+1) % nRow ; }
void CreateToroidalMatrix(void) {
int a,b, i, j;
for(a = 0 ; a <= nRow ; a++) {
for(b=0 ; b < nCol ; b++) {
if(Data[a][b]) {
Matrix[a][b].RowIndex = a;
Matrix[a][b].ColIndex = b;
// Left pointer
i = a; j = b; do {j = dataLeft(j); } while (!Data[i][j]);
Matrix[a][b].Left = &Matrix[i][j];
// Right pointer
i = a; j = b; do {j = dataRight(j); } while (!Data[i][j]);
Matrix[a][b].Right = &Matrix[i][j];
// Up pointer
i = a; j = b; do {i = dataUp(i); } while (!Data[i][j]);
Matrix[a][b].Up = &Matrix[i][j];
// Down pointer
i = a; j = b; do {i = dataDown(i); } while (!Data[i][j]);
Matrix[a][b].Down = &Matrix[i][j];
//Head pointer
Matrix[a][b].Header = &Matrix[0][b];
Matrix[a][b].HeaderID = b+1;
}
}
}
//Initialize root
RootNode->Right = &Matrix[0][0];
RootNode->Left = &Matrix[0][nCol-1];
Matrix[0][0].Left = RootNode;
Matrix[0][nCol-1].Right = RootNode;
}
void Cover(struct str_node *ColNode){
cout<<"Covering header node "<<ColNode->HeaderID<<'\n';
struct str_node *RowNode, *RightNode;
ColNode->Right->Left = ColNode->Left;
ColNode->Left->Right = ColNode->Right;
for(RowNode = ColNode->Down ; RowNode!=ColNode ; RowNode = RowNode->Down) {
for(RightNode = RowNode->Right ; RightNode!=RowNode ; RightNode = RightNode->Right) {
RightNode->Up->Down = RightNode->Down;
RightNode->Down->Up = RightNode->Up;
}
}
}
void UnCover(struct str_node *ColNode) {
//uncover the covered nodes to find a different solution
struct str_node *RowNode, *LeftNode;
for(RowNode = ColNode->Up; RowNode!=ColNode; RowNode = RowNode->Up) {
for(LeftNode = RowNode->Left; LeftNode!=RowNode; LeftNode = LeftNode->Left) {
LeftNode->Up->Down = LeftNode;
LeftNode->Down->Up = LeftNode;
}
}
ColNode->Right->Left = ColNode;
ColNode->Left->Right = ColNode;
}
void Search(int k){
//all columns covered
if( RootNode->Right == RootNode){
cout<<"found\n";
if(maxResult < k)
maxResult = k;
return;
}
//if not covered
else{
struct str_node *Column = RootNode->Right;
struct str_node *RowNode;
struct str_node *RightNode;
struct str_node *LeftNode;
Cover(Column);
for( RowNode = Column->Down ; RowNode!=Column ; RowNode = RowNode->Down){
ResultRow.push_back(RowNode);
for(RightNode = RowNode->Right; RightNode!=RowNode; RightNode = RightNode->Right)
Cover(RightNode->Header);
Search(k+1);
RowNode = ResultRow.back();
ResultRow.pop_back();
Column = RowNode->Header;
for(LeftNode = RowNode->Left; LeftNode!=RowNode; LeftNode = LeftNode->Left)
UnCover(LeftNode->Header);
}
UnCover(Column);
}
}
void GetData(void){
int pos,k;
scanf("%d%d",&nCol, &nRow);
for(int i=0 ; i<nCol ; i++)
Data[0][i] = true;
for(int i=1 ; i<=nRow ; i++){
scanf("%d",&k);
for(int j=0 ; j<k ; j++){
scanf("%d",&pos);
Data[i][pos-1] = true;
}
}
CreateToroidalMatrix();
}
int main(void){
GetData();
Search(0); // from level 0
printf("%d\n",maxResult+1);
return 0;
}
#包括
#包括
#包括
#包括
#定义最大行50L
#定义最大列100L
使用名称空间std;
结构str_节点{
结构str_节点*头;
结构str_节点*左;
结构str_节点*右侧;
结构str_节点*Up;
结构str_节点*向下;
int HeaderID、ROWDINDEX、ColIndex;
};
int nCol;
int nRow;
结构str_节点矩阵[MAX_ROW][MAX_COL];
vectorResultRow;
结构str_节点根;
struct str_node*RootNode=&Root;
布尔数据[最大行][最大列];
int-maxResult;
//获取邻居的函数(是循环函数)
内联int-dataLeft(inti){return(i-1<0)?nCol-1:i-1;}
内联int-dataRight(inti){return(i+1)%nCol;}
内联int-dataUp(inti){return(i-1<0)?nRow-1:i-1;}
内联int-dataDown(inti){return(i+1)%nRow;}
void CreateToroidalMatrix(void){
int a,b,i,j;
对于(a=0;a右=&矩阵[0][0];
RootNode->Left=&矩阵[0][nCol-1];
矩阵[0][0]。左=根节点;
矩阵[0][nCol-1]。右=根节点;
}
空洞覆盖(结构str_节点*ColNode){
coutRight=ColNode->Right;
对于(RowNode=ColNode->Down;RowNode!=ColNode;RowNode=RowNode->Down){
对于(RightNode=RowNode->Right;RightNode!=RowNode;RightNode=RightNode->Right){
右节点->向上->向下=右节点->向下;
右节点->向下->向上=右节点->向上;
}
}
}
void discover(结构str_节点*ColNode){
//揭开覆盖的节点以找到不同的解决方案
结构str_节点*RowNode,*LeftNode;
对于(RowNode=ColNode->Up;RowNode!=ColNode;RowNode=RowNode->Up){
对于(LeftNode=RowNode->Left;LeftNode!=RowNode;LeftNode=LeftNode->Left){
LeftNode->Up->Down=LeftNode;
LeftNode->Down->Up=LeftNode;
}
}
ColNode->Right->Left=ColNode;
ColNode->Left->Right=ColNode;
}
无效搜索(INTK){
//所有栏目都包括在内
if(RootNode->Right==RootNode){
coutDown;RowNode!=列;RowNode=RowNode->Down){
ResultRow.push_back(行节点);
对于(RightNode=RowNode->Right;RightNode!=RowNode;RightNode=RightNode->Right)
封面(右节点->标题);
搜索(k+1);
RowNode=ResultRow.back();
ResultRow.pop_back();
列=行节点->标题;
对于(LeftNode=RowNode->Left;LeftNode!=RowNode;LeftNode=LeftNode->Left)
揭开(左节点->标题);
}
揭(柱);
}
}
void GetData(void){
int pos,k;
scanf(“%d%d”,&nCol,&nRow);
对于(inti=0;iOk),我再次检查了源代码并找到了bug,忘记了在GetData(void)中增加nRow
。这些小错误让人毛骨悚然!下面是代码的修改部分,现在它工作得很好。nRow
必须增加一次,因为我为每列的标题使用了一个额外的行
void GetData(void){
int pos,k;
scanf("%d%d",&nCol, &nRow);
nRow++;//this is the change
for(int i=0 ; i<nCol ; i++)
Data[0][i] = true;
for(int i=1 ; i<nRow ; i++){
scanf("%d",&k);
for(int j=0 ; j<k ; j++){
scanf("%d",&pos);
Data[i][pos-1] = true;
}
}
CreateToroidalMatrix();
}
因为nRow比它应该的小一个,所以内联函数用于获取邻居,特别是dataUp()
和dataDown()
返回了意外的值。我不能肯定,但是因为你修改了矩阵的结构,你可能打破了的封面
和揭开
函数。谢谢你,这看起来像是一个很酷的博客。我看到许多其他数独的实现几乎都有相同的代码,然后当我翻阅Donald Knuth的原始论文时,我发现这一切都是从那里开始的:D@AndyG封面
和揭开
都很好:)
for(a=0 ; a<nRow ; a++) // removed equal sign