first 7 Introductory problems

CSES - CSES Problem Set/Permutations.cpp

@@ -0,0 +1,30 @@
+//  Permutations
+
+#include<bits/stdc++.h>
+
+using namespace std;
+
+int main() {
+    int n; cin >> n;
+    if (n  == 2 || n == 3) {
+        cout << "NO SOLUTION" << endl;
+        return 0;
+    }
+    if (n & 1) {
+        for (int i = n; i >= 1; i -= 2) {
+            cout << i << " ";
+        }
+        for (int i = n-1; i > 1; i -= 2) {
+            cout << i << " ";
+        }
+    } else {
+        for (int i = n - 1; i >= 1; i -= 2) {
+            cout << i << " ";
+        }
+        for (int i = n; i > 1; i -= 2) {
+            cout << i << " ";
+        }
+    }
+    cout << endl;
+    return 0;
+}