Tontti

#include <iostream>
#include <vector>
using namespace std;
 
int main(int argc, char** argv) {
    int n, m, x;
    cin >> n >> m >> x;
    int r = 1;
    while (r*r < x) ++r;
    vector<string> w;
    vector<int> kv, tv, kkv, ttv;
    string s;
    int kk = 0;
    for (int i = 0; i < n; ++i){
        kkv.push_back(0);
        cin >> s;
        w.push_back(s);
        for(int j = 0; j < m; ++j){
            if (i == 0) ttv.push_back(0);
            if (s[j] == '*') {
                if (i < r) ttv.at(j) += 1;
                if (j < r-1) kkv.at(i) += 1;
                if (i < r-1 && j < r-1) ++kk;
            }
        }
    }
    int v = 0;
    for(; r <= (n < m ? n : m); ++r){
        int k = kk;
        tv = ttv;
        kv = kkv;
        for(int i = 0; i <= n-r; ++i){
            k += kv.at(i+r-1);
            if (i > 0) k -= kv.at(i-1);
            int t = k;
            for (int j = 0; j <= m-r; ++j){
                t += tv.at(j+r-1);
                if (j > 0) t -= tv.at(j-1);
                if (i == 0 && j == 0) kk = t;
                if (t == x) ++v;
            }
            if (i+r < n) {  
                for (int j = 0; j < m; ++j){
                    if (w.at(i)[j] == '*') tv.at(j) -= 1;
                    if (w.at(i+r)[j] == '*') tv.at(j) += 1;
                }
            }
        }
        if (r < n && r < m) {
            for(int i = 0; i < n; ++i){
                if (w.at(i)[r-1] == '*') kkv.at(i) += 1;
            }
            for (int j = 0; j < m; ++j){
                if (w.at(r)[j] == '*') ttv.at(j) += 1; 
            }   
        }
    }
    cout << v;
    return 0;
}

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: TIME LIMIT EXCEEDED

Test 14

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 15

Group: 3

Verdict: TIME LIMIT EXCEEDED