Merge pull request #177 from Kaizo8/shreshth

easy/day_20/solution.cpp

@@ -1 +1,36 @@
-//write your code here
+#include <bits/stdc++.h>
+using namespace std;
+int main(){
+    int t;
+    cin >> t;
+    while(t--){
+        int n;
+        cin >> n;
+        if(n == 1){
+            cout << 1 << endl;
+            continue;
+        }
+        else if(n == 2){
+            cout << 1 << " " << 2 <<endl;
+            continue;
+        }
+        else if(n%2 !=0){
+             cout << -1 << endl;
+             continue;
+        }
+        else {
+            int arr[n];
+            for(int i = 1 ; i<= n ; i++){
+                arr[i] = i;
+                if(i%2 == 0) {
+                    swap(arr[i] ,arr[i-1]);
+                }
+            }
+            for(int i = 1 ; i <= n ; i++){
+                cout << arr[i] << " ";
+            }
+            cout << endl;
+        }
+    }
+    return 0;
+}