DLX精确覆盖.....模版题
Sudoku
| Time Limit: 1000MS |
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Memory Limit: 65536K |
| Total Submissions: 8336 |
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Accepted: 2945 |
Description In the game of Sudoku, you are given a large 9 × 9 grid divided into smaller 3 × 3 subgrids. For example,
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Given some of the numbers in the grid, your goal is to determine the remaining numbers such that the numbers 1 through 9 appear exactly once in (1) each of nine 3 × 3 subgrids, (2) each of the nine rows, and (3) each of the nine columns. Input The input test file will contain multiple cases. Each test case consists of a single line containing 81 characters, which represent the 81 squares of the Sudoku grid, given one row at a time. Each character is either a digit (from 1 to 9) or a period (used to indicate an unfilled square). You may assume that each puzzle in the input will have exactly one solution. The end-of-file is denoted by a single line containing the word “end”. Output For each test case, print a line representing the completed Sudoku puzzle. Sample Input .2738..1..1...6735.......293.5692.8...........6.1745.364.......9518...7..8..6534.
......52..8.4......3...9...5.1...6..2..7........3.....6...1..........7.4.......3.
end Sample Output 527389416819426735436751829375692184194538267268174593643217958951843672782965341
416837529982465371735129468571298643293746185864351297647913852359682714128574936 Source Stanford Local 2006 |
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#include
#include
#include
#include
using namespace std; const int N=9; const int maxn=N*N*N+10; const int maxm=N*N*4+10; const int maxnode=maxn*4+maxm+10; char sudoku[maxn]; struct DLX { int n,m,size; int U[maxnode],D[maxnode],L[maxnode],R[maxnode],Row[maxnode],Col[maxnode]; int H[maxnode],S[maxnode]; int ansd,ans[maxn]; void init(int _n,int _m) { n=_n; m=_m; for(int i=0;i<=m;i++) { S[i]=0; U[i]=D[i]=i; L[i]=i-1; R[i]=i+1; } R[m]=0; L[0]=m; size=m; for(int i=1;i<=n;i++) H[i]=-1; } void Link(int r,int c) { ++S[Col[++size]=c]; Row[size]=r; D[size]=D[c]; U[D[c]]=size; U[size]=c; D[c]=size; if(H[r]<0) H[r]=L[size]=R[size]=size; else { R[size]=R[H[r]]; L[R[H[r]]]=size; L[size]=H[r]; R[H[r]]=size; } } void remove(int c) { L[R[c]]=L[c]; R[L[c]]=R[c]; for(int i=D[c];i!=c;i=D[i]) for(int j=R[i];j!=i;j=R[j]) { U[D[j]]=U[j]; D[U[j]]=D[j]; --S[Col[j]]; } } void resume(int c) { for(int i=U[c];i!=c;i=U[i]) for(int j=L[i];j!=i;j=L[j]) ++S[Col[U[D[j]]=D[U[j]]=j]]; L[R[c]]=R[L[c]]=c; } bool Dance(int d) { if(R[0]==0) { for(int i=0;i