Uvalive 4997 ABCD Tiles--dfs

Test instructions: NxN map, there is a color of the tile and some space points, to use the b,c,d color to fill these spaces, only a cross-shaped fill, but also to ensure that the common or common side of the lattice can not be the same color, a dictionary order the smallest fill method, if not, output "not Possible".

Solution: From the top down, if there is a space, then it must be the bottom of the grid to fill the cross tile to fill in this space, so this we will mark this space, and the following three and below a space to assign a different value, do not let the scan after scanning, those are not spaces, directly jump out can. So we can find all the need to fill the number of 10-shaped tiles, and know the location of the lattice, then just consider what color to dye things, because there are only three colors, so DFS to fill, if to a certain state to find which color can not fill, then backtracking. This until the staining scheme location is successfully found.

Code:

#include <iostream>#include<cstdio>#include<cstring>#include<cstdlib>#include<cmath>#include<algorithm>using namespacestd;Charmp[ -][ -];intN,tot;intcol[4];BOOLOK (intXintY) {returnX >=0&& x < n && y >=0&& y <N;}BOOLFindcolor (intIintJCharch) {memset (col,0,sizeof(col)); if(OK (i+1, j+1) && mp[i+1][j+1] !='.') col[mp[i+1][j+1]-'A']++; if(OK (i+1, J-1) && mp[i+1][j-1] !='.') col[mp[i+1][j-1]-'A']++; if(OK (I-1, J-1) && mp[i-1][j-1] !='.') col[mp[i-1][j-1]-'A']++; if(OK (I-1, j+1) && mp[i-1][j+1] !='.') col[mp[i-1][j+1]-'A']++;  for(intk=j-1; k<=j+1; k++)if(OK (i+2, k) && mp[i+2][K]! ='.') col[mp[i+2][k]-'A']++;  for(intk=i-1; k<=i+1; k++)if(OK (k,j+2) && mp[k][j+2] !='.') col[mp[k][j+2]-'A']++;  for(intk=j-1; k<=j+1; k++)if(OK (I-2, k) && mp[i-2][K]! ='.') col[mp[i-2][k]-'A']++;  for(intk=i-1; k<=i+1; k++)if(OK (k,j-2) && mp[k][j-2] !='.') col[mp[k][j-2]-'A']++; if(col[ch-'A'])return true; return false;}voidColorintIintJCharch) {Mp[i][j]= mp[i-1][J] = mp[i][j+1] = mp[i+1][J] = mp[i][j-1] =ch;}structNode {intx, y; Node (int_x,int_y): X (_x), Y (_y) {} node () {}}p[255];BOOLDfsintc) {if(c = = tot)return true; C++; intx = p[c].x, y =p[c].y;  for(intI=1; i<=3; i++) {//b,c,d        if(!findcolor (x, Y,'A'+i)) {//around there's no ' A ' +i this colorColor (x, Y,'A'+i); if(Dfs (c))return true; Color (x, Y,'.'); }    }    return false;}intMain () {intT,cs =1, I,j,k,h; scanf ("%d",&t);  while(t--) {scanf ("%d",&N); intSpace =0;  for(i=0; i<n;i++) scanf ("%s", Mp[i]); intFlag =1; Tot=0;  for(i=0; i<n;i++) {             for(j=0; j<n;j++) {                if(Mp[i][j] = ='.') {                     for(k=j-1; k<=j+1; k++) {                        if(! OK (i+1, k) | | mp[i+1][K]! ='.') {flag =0; Break; } Elsemp[i+1][K] ='#'; }                    if(! OK (i+2, j) | | mp[i+2][J]! ='.') {flag =0; Break; } Elsemp[i+2][J] ='#'; p[++tot] = node (i+1, j);//Coloring Center Point}}} printf ("Case %d:", cs++); if(!flag) {Puts ("Not possible!");Continue; } if(Dfs (0) {puts ("");  for(i=0; i<n;i++)            {                 for(j=0; j<n;j++) printf ("%c", Mp[i][j]); Puts (""); }        }        ElsePuts"Not possible!"); }    return 0;}

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Uvalive 4997 ABCD Tiles--dfs