P1219 [USACO1.5]八皇后 Checker Challenge

R41967120

problem/P1219/P1219.cpp

@@ -0,0 +1,33 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, ans, a[200], b[200], dg[200], udg[200];
+
+void dfs(int i) {
+    if (i > n) {
+        if (ans < 3) {
+            for (int j = 1; j <= n; j++) {
+                cout << a[j] << ' ';
+            }
+            cout << endl;
+        }
+        ans++;
+        return;
+    }
+    for (int j = 1; j <= n; j++) {
+        if (!b[j] && !dg[i + j] && !udg[n - j + i]) {
+            a[i] = j;
+            b[j] = dg[i + j] = udg[n - j + i] = true;
+            dfs(i + 1);
+            b[j] = dg[i + j] = udg[n - j + i] = false;
+        }
+    }
+}
+
+int main() {
+    cin >> n;
+    dfs(1);
+    cout << ans << endl;
+    return 0;
+}