Pair sort

input/code.cpp: In function 'void Test()':
input/code.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   15 |     freopen("temp\\in.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
input/code.cpp: In function 'int main()':
input/code.cpp:21:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
input/code.cpp:24:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |         scanf("%d", &a[i]);
      |         ~~~~~^~~~~~~~~~~~~

#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
typedef long long LL;
typedef std::pair<int, int> poi;
using std::make_pair;
using std::vector;
const int N=100005;

int a[2*N], b[2*N];
poi p[N], pr[N];
void Test()
{
    freopen("temp\\in.txt", "r", stdin);
}
int main()
{
    // Test();
    int n, k=0, kr=0;
    scanf("%d", &n);
    for(int i=1; i<=2*n; i++)
    {
        scanf("%d", &a[i]);
        b[i] = a[i];
        if(p[a[i]].first == 0)
        {  
            p[a[i]].first = i;
        } else {
            p[a[i]].second = i;
        }
    }

    for(int i=1; i<=n; i++)
        pr[i] = make_pair(p[i].first, p[i].second);

    vector<poi> ans, ansr;
    for(int i=1; i<=2*n; i+=2)
    {
        if(a[i] == a[i+1])
            continue;
        k++;
        // swap i+1, j
        poi px = p[a[i]], py = p[a[i+1]];
        int j = px.second;
        py.first = j;
        std::swap(a[i+1], j);
        if(py.first > py.second)
            std::swap(py.first, py.second);
        ans.push_back(make_pair(i+1, j));
    }

    for(int i=1; i<=2*n; i+=2)
    {
        if(b[i] == b[i+1])
            continue;
        kr++;
        // swap i, j
        poi px = pr[b[i+1]], py = pr[b[i]];
        int j = px.second;
        py.first = j;
        std::swap(b[i], b[j]);
        if(py.first > py.second)
            std::swap(py.first, py.second);
        ansr.push_back(make_pair(i, j));
    }
// printf("%d %d\n", k, kr);
    if(k <= kr)
    {
        printf("%d\n", k);
        for(auto it = ans.begin(); it != ans.end(); it++)
            printf("%d %d\n", (*it).first, (*it).second);
    } else {
        printf("%d\n", kr);
        for(auto it = ansr.begin(); it != ansr.end(); it++)
            printf("%d %d\n", (*it).first, (*it).second);
    }
    
    return 0;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER