done 3 sorting problems

CSES - CSES Problem Set/Introducotry_Problems/Chessboard_and_Queens.cpp

@@ -0,0 +1,38 @@
+//  Chessboard and Queens
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+bool is_not_attacking(vector<pair<int, int>> &p, pair<int, int> n) {
+    for (auto &[x, y]: p) {
+        if (x == n.first || y == n.second) return false;
+        if (abs(x - n.first) == abs(y - n.second)) return false;
+    }
+    return true;
+}
+
+int queens(vector<string> &input, int row, vector<pair<int, int>> &placed) {
+    if (row == input.size()) return 1;
+    int possibilities = 0;
+    for (int i{}; i < 8; i++) {
+        if (input[row][i] != '*' && is_not_attacking(placed, {i, row})) {
+            placed.push_back({i, row});
+            possibilities += queens(input, row + 1, placed);
+            placed.pop_back();
+        }
+    }
+    return possibilities;
+}
+
+int main() {
+    vector<string> input;
+    for (int i{}; i < 8; i++) {
+        string line;
+        cin >> line;
+        input.push_back(line);
+    }
+    vector<pair<int, int>> placed;
+    cout << queens(input, 0, placed) << endl;
+    return 0;
+}