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#include "leetcode.h"
class Solution {
public:
int totalNQueens(int n) {
vector<bool> col(n, true);
vector<bool> anti(2 * n - 1, true);
vector<bool> main(2 * n - 1, true);
vector<int> row(n, 0);
int count = 0;
helper(0, row, col, main, anti, count);
return count;
}
private:
void helper(int i, vector<int> &row, vector<bool> &col, vector<bool> &main,
vector<bool> &anti, int &count) {
if (i == row.size()) {
count++;
return;
}
for (int j = 0; j < col.size(); j++)
if (col[j] && main[i + j] && anti[i + col.size() - 1 - j]) {
row[i] = j;
col[j] = main[i + j] = anti[i + col.size() - 1 - j] = false;
helper(i + 1, row, col, main, anti, count);
col[j] = main[i + j] = anti[i + col.size() - 1 - j] = true;
}
}
};
int main() {
Solution obj;
cout << obj.totalNQueens(4);
}
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