Tontti

#include <iostream>
#include <vector>
#include <algorithm>

using std::cin;
using std::cout;
using std::cerr;
using std::endl;
using std::vector;

int main () {
  int n, m, num, val;
  int min, cur;
  int result(0);
  char c;
  cin >> n >> m >> num;


  vector<vector<int> > table(n+1, vector<int>(m+1, 0));

  if (num > 0) {

    for (int i = 1; i <=  n; ++i) {
      for (int j = 1; j <=  m; ++j) {
        cin >> c;
        if (c == '*') {
          val = 1;
        } else {
          val = 0;
        }
        table[i][j] = val + table[i][j-1]  + table[i-1][j] - table[i-1][j-1];
      }
    }

    min = (int) ceil(sqrt(num));
    //cerr << table[n][m] << " min=" << min  << endl;

    for (int i = 0; i <=  n-min; ++i) {
      for (int j = 0; j <=  m-min; ++j) {
        int begin = min;
        int end = std::min(n-i, m-j);
        //cerr  << endl << i << "-" << j << endl;
        while (begin <= end) {
          cur = (end + begin)/2;
          val = table[i][j] - table[i+cur][j]  -  table[i][j+cur] + table[i+cur][j+cur];
          //cerr << cur << ": " << val << endl;
          if (val == num) {
            int left = cur;
            while (left != begin) {
              int z = (left + begin) / 2;
              val = table[i][j] - table[i+z][j]  -  table[i][j+z] + table[i+z][j+z];
              if (val == num) {
                left = z;
              } else {
                begin = z + 1;
              }
            }
            int right = cur;
            while (right != end) {
              int z = (right + end + 1) / 2;
              val = table[i][j] - table[i+z][j]  -  table[i][j+z] + table[i+z][j+z];
              if (val == num) {
                right = z;
              } else {
                end = z - 1;
              }
            }
            result += 1 + right - left;
            //cerr << "HIT " << result << endl;
            break;
          }
          if (val > num) {
            end = cur - 1;
          } else {
            begin = cur + 1;
          }
        }
      }
    }

  } else {
    //cerr << "zero" << endl;
    for (int i = 1; i <=  n; ++i) {
      for (int j = 1; j <=  m; ++j) {
        cin >> c;
        if (c != '*') {
          table[i][j] = 1 + std::min(table[i][j-1], std::min(table[i-1][j], table[i-1][j-1]));
          result += table[i][j];
        }
      }
    }
  }

  cout << result << endl;
  return 0;
}

Test 1

Subtask: 1

Verdict: ACCEPTED

Test 2

Subtask: 1

Verdict: ACCEPTED

Test 3

Subtask: 1

Verdict: ACCEPTED

Test 4

Subtask: 1

Verdict: ACCEPTED

Test 5

Subtask: 1

Verdict: ACCEPTED

Test 6

Subtask: 2

Verdict: ACCEPTED

Test 7

Subtask: 2

Verdict: ACCEPTED

Test 8

Subtask: 2

Verdict: ACCEPTED

Test 9

Subtask: 2

Verdict: ACCEPTED

Test 10

Subtask: 2

Verdict: ACCEPTED

Test 11

Subtask: 3

Verdict: ACCEPTED

Test 12

Subtask: 3

Verdict: ACCEPTED

Test 13

Subtask: 3

Verdict: ACCEPTED

Test 14

Subtask: 3

Verdict: ACCEPTED

Test 15

Subtask: 3

Verdict: ACCEPTED