Deranging Hat

#include <bits/stdc++.h>
using namespace std;
int main() {
  string s; 
  cin >> s;
  int n = s.length();
  vector<pair<int,int>> st;
  for(int i=0;i<n;i++) {
    int m = s[i];
    int mi = i;
    for(int j=i+1;j<n;j++) {
      if(m>s[j])m=s[j],mi=j;
    }
    if(mi==i)continue;
    std::swap(s[i],s[mi]);
    st.emplace_back(i,mi);
  }
  while(st.size()){
    int a,b;
    tie(a,b) = st.back();
    st.pop_back();
    cout<<b+1<<' '<<a+1<<'\n';
  }
  return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED