uva297 (Quadtree)

Give us two quadtree of the pre-sequence traversal, want me to ask the original 32*32 matrix how many positions are black

Quardtree is to divide the area into equal 4 sub-spaces, and then recursively divide the 4 sub-spaces, knowing that the termination is broken after the condition is met

The termination condition of this problem is that it encounters a black or white node that stops recursion.

As for why a pre-order traversal can make a contribution, it is because of the color of the knot, so it is possible to know when to return recursively. So I can build a lesson tree

There is nothing to play Java code, anyway, C + + syntax are very familiar with the Java brush problems, brush questions, learn Java two not mistaken

1 ImportJava.util.Scanner;2 3 4  Public classMain {5     StaticScanner cin =NewScanner (system.in);6     Final Static intLEN = 32;7     Static intAns = 0;8     StaticString str;9     Static intp;Ten     Static int[] Mat =New int[Len][len]; One      Public Static voidDfsintRintCintW) {//(R,C) is the upper left corner A          -         Charch = Str.charat (p++); -         if(ch== ' P '){ theDFS (R,C+W/2,W/2);//for section 1 in the diagram, -DFS (R,C,W/2);//for section 2 in the diagram, -DFS (R+W/2,C,W/2);//for section 3 in the diagram, -DFS (R+W/2,C+W/2,W/2);//for area 4 in the diagram, +         } -         Else if(ch== ' F ') {//fills a rectangle if it encounters a black node . +              for(intk=0; i<r+w; ++i) A                  for(intJ=c; j<c+w; ++j) at                 if(mat[i][j]==0) {//because it is a combination of two trees, it is possible to repeat the fill, so only when the padding is 0 ans++ -MAT[I][J] = 1; -ans++; -                 } -         } -     } in      Public Static voidinit () { -Ans = 0; to          for(inti=0; i<len; ++i) +              for(intj=0; j<len; ++j) -MAT[I][J] = 0; the     } *      Public Static voidMain (string[] args) { $         intN;Panax Notoginseng          -n =cin.nextint (); the cin.nextline (); +          for(inti=0; i<n; ++i) { A init (); thep = 0; +str =cin.nextline (); -DFS (0,0, LEN); $p = 0; $str =cin.nextline (); -DFS (0,0, LEN); -System.out.println ("There is" +ans+ "black pixels."); the         } -     }Wuyi  the}

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uva297 (Quadtree)