cf516b Drazil and Tiles

cf516b Drazil and Tiles

​​ Drazil created a following problem about putting 1 × 2 tiles into an n × m grid:

“There is a grid with some cells that are empty and some cells that are occupied. You should use 1 × 2 tiles to cover all empty cells and no two tiles should cover each other. And you should print a solution about how to do it.”

But Drazil doesn’t like to write special checking program for this task. His friend, Varda advised him: “how about asking contestant only to print the solution when it exists and it is unique? Otherwise contestant may print ‘Not unique’ “.

Drazil found that the constraints for this task may be much larger than for the original task!

Can you solve this new problem?

Note that you should print ‘Not unique’ either when there exists no solution or when there exists several different solutions for the original task.

Input The first line contains two integers n and m (1 ≤ n, m ≤ 2000).

The following n lines describe the grid rows. Character ‘.’ denotes an empty cell, and the character ‘*’ denotes a cell that is occupied.

Output If there is no solution or the solution is not unique, you should print the string “Not unique”.

Otherwise you should print how to cover all empty cells with 1 × 2 tiles. Use characters “<>” to denote horizontal tiles and characters “^v” to denote vertical tiles. Refer to the sample test for the output format example.

Examples Input 3 3 … .*. … Output Not unique Input 4 4 ..** *… .* …. Output <>** *^<> v* <><> Input 2 4 .. …. Output <> <><> Input 1 1 . Output Not unique Input 1 1 * Output * Note In the first case, there are indeed two solutions:

<>^ ^*v v<> and

^<> v*^ <>v so the answer is “Not unique”.

再一次低级错误 n写成char格式 网站直接无输出

#include#include#include#define N 2200struct node{ int x1,y1,x2,y2;};std::queue q;int x[5]={0,-1,1,0,0},y[5]={0,0,0,1,-1};bool visit[N][N];char mp[N][N];int n,m;inline void solve(int i,int j){ if(visit[i][j]) return; int cnt=0; if (mp[i][j]=='.'){ for (int z=1;z<=4;++z) if (i+x[z]<=n&&i+x[z]>0&&j+y[z]<=m&&j+y[z]>0){ int x1=i+x[z],y1=j+y[z]; if (mp[x1][y1]=='.'&&!visit[x1][y1]) cnt++; } if (cnt==1){ node tmp;tmp.x1=i;tmp.y1=j; for (int z=1;z<=4;++z) if (i+x[z]<=n&&i+x[z]>0&&j+y[z]<=m&&j+y[z]>0){ int x1=i+x[z],y1=j+y[z]; if (mp[x1][y1]=='.'&&!visit[x1][y1]) tmp.x2=x1,tmp.y2=y1,q.push(tmp),visit[x1][y1]=true,visit[i][j]=true; } } }}inline void solve1(int i,int j){ for (int z=1;z<=4;++z) if (i+x[z]<=n&&i+x[z]>0&&j+y[z]<=m&&j+y[z]>0){ int x1=i+x[z],y1=j+y[z]; if (mp[x1][y1]=='.'&&!visit[x1][y1]) solve(x1,y1); }}int main(){ freopen("cf.in","r",stdin);// freopen("cf.out","w",stdout); scanf("%d%d",&n,&m); for (int i=1;i<=n;++i) scanf("%s",mp[i]+1); for (int i=1;i<=n;++i) for (int j=1;j<=m;++j) if (mp[i][j]=='*') visit[i][j]=true; for (int i=1;i<=n;++i) for (int j=1;j<=m;++j) solve(i,j); while (!q.empty()){ node tmp=q.front();q.pop(); int x1=tmp.x1,x2=tmp.x2,y1=tmp.y1,y2=tmp.y2; if (y1';solve1(x2,y2);continue;} if (y1>y2){mp[x1][y1]='>';mp[x2][y2]='<';solve1(x2,y2);continue;} if (x1x2){mp[x1][y1]='v';mp[x2][y2]='^';solve1(x2,y2);continue;} } for (int i=1;i<=n;++i) for (int j=1;j<=m;++j) if (mp[i][j]=='.') {printf("Not unique");return 0;} for (int i=1;i<=n;++i) printf("%s\n",mp[i]+1); return 0;}

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