t=int(input())
for _ in range(t):
n=int(input())
if n%2==0:
i=1
while(i<=n):
print(i+1,end=" ")
print(i,end=" ")
i+=2
else:
print(1,end=" ")
i=2
while(i<=n):
print(i+1,end=" ")
print(i,end=" ")
i+=2
print()
#include<bits/stdc++.h>
using namespace std;
#define int long long int
int32_t main(){
int t;
cin>>t;
while(t--){
int n;
cin>>n;
int a[n+1];
for(int i=1;i<n+1;++i){
a[i]=i;
}
for(int i=1;i<n+1;++i){
if(n%2==0){
if(i%2!=0){
swap(a[i],a[i+1]);
}}
else{
if(i%2==0 && i!=1){
swap(a[i],a[i+1]);
}}
}
for(int i=1;i<n+1;++i){
cout<<a[i]<<" ";
}cout<<endl;
}
}198. House Robber | 153. Find Minimum in Rotated Sorted Array |
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102. Binary Tree Level Order Traversal | 96. Unique Binary Search Trees |
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50. Pow(x, n) | 43. Multiply Strings |
34. Find First and Last Position of Element in Sorted Array | 33. Search in Rotated Sorted Array |
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1092. Shortest Common Supersequence | 1044. Longest Duplicate Substring |
1032. Stream of Characters | 987. Vertical Order Traversal of a Binary Tree |
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174. Dungeon Game | 127. Word Ladder |