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| class Solution {
using LL = long long;
public:
bool check(vector<vector<int>>& g, int a, int b, int c, int d) {
LL sum = 0;
for (int i = a; i <= c; ++i) {
LL s = 0;
for (int j = b; j <= d; ++j) s += g[i][j];
if (sum && sum != s) return false;
sum = s;
}
for (int i = b; i <= d; ++i) {
LL s = 0;
for (int j = a; j <= c; ++j) s += g[j][i];
if (sum != s) return false;
}
LL s = 0;
for (int i = a, j = b; i <= c; ++i, ++j)
s += g[i][j];
if (s != sum) return false;
s = 0;
for (int i = a, j = d; i <= c; ++i, --j)
s+= g[i][j];
return s == sum;
}
int largestMagicSquare(vector<vector<int>>& g) {
const int n = g.size(), m = g[0].size();
for (int k = min(n, m); k >= 2; --k) {
for (int i = 0 ; i + k - 1 < n; ++i) {
for (int j = 0; j + k - 1 < m; ++j) {
if (check(g, i, j, i + k - 1, j + k - 1))
return k;
}
}
}
return 1;
}
};
|