Tontti

 
public class Tontti{
    
    public static void main(String[] args){
        IO io = new IO();
        
        int n = io.nextInt(), m = io.nextInt(), x = io.nextInt();
        
        String row;
        
        int[][] metaTrees = new int[n + 1][m + 1];
        
        for(int i = 0; i < n; i++){
            row = io.next();
            
            for(int j = 0; j < m; j++){
                
                metaTrees[i + 1][j + 1] = metaTrees[i][j + 1] + metaTrees[i + 1][j] - metaTrees[i][j];
                
                if(row.charAt(j) == '*')
                    metaTrees[i + 1][j + 1]++;
            }
        }
        
//        for(int i = 0; i < n; i++){
//            for(int j = 0; j < m; j++){
//                io.print(metaTrees[i + 1][j + 1] + " ");
//            }
//            io.println();
//        }
        
        
        int ans = 0, treeCount, minSize = (int)Math.ceil(Math.sqrt(x)) - 1;
        
        for(int i = 0; i + minSize < n; i++){
            for(int j = 0; j + minSize < m; j++){
                
                for(int k = minSize; i + k < n && j + k < m; k++){
                    
                    treeCount = metaTrees[i + k + 1][j + k + 1]
                            - metaTrees[i + k + 1][j]
                            - metaTrees[i][j + k + 1]
                            + metaTrees[i][j];
                    
                    if(treeCount == x)
                        ans++;
                    else if(treeCount > x)
                        break;
                    else if(treeCount < x - 2 * k)
                        k = (int)Math.sqrt(x - treeCount + k * k) - 1;
                }
                
            }
        }
        
        io.println(ans);
        io.close();
    }
    
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED