Pair sort

#![allow(unused)]

use std::{io, thread::spawn};

fn take_int() -> usize {
    let mut input = String::new();
    io::stdin().read_line(&mut input).unwrap();
    return input.trim().parse::<usize>().unwrap();
}

fn take_vector() -> Vec<(usize, usize)> {
    let mut input = String::new();
    io::stdin().read_line(&mut input).unwrap();
    let arr: Vec<(usize, usize)> = input
        .trim()
        .split_whitespace()
        .map(|x| x.parse::<usize>().unwrap())
        .enumerate()
        .collect();
    return arr;
}

fn main() {
    let mut n: usize = take_int();
    let mut arr: Vec<(usize, usize)> = take_vector();
    let mut sorted = arr.clone();
    // println!("{:?}", arr);

    sorted.sort_unstable_by_key(|k| k.1);

    let mut i = 0;
    let mut count_swaps = 0;
    let mut swaps: Vec<(usize, usize)> = Vec::with_capacity(n);
    while i < n {
        let current = arr[i];
        if arr[i + 1] != current {
            count_swaps += 1;
            // needs swap with
            let index = sorted[current.1 * 2 + 1].0;
            // println!("index to change {}", index);
            swaps.push((i, index));

            let temp = arr[index];
            arr[index] = arr[i + 1];
            arr[i + 1] = temp;

            sorted[i * 2 + 1] = arr[i + 1];
        }
        // println!("{:?}", arr);
        i += 2;
    }
    println!("{}", count_swaps);
    for i in 0..swaps.len() {
        println!("{} {}", swaps[i].0+1, swaps[i].1+1);
    }
}

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: RUNTIME ERROR

thread 'main' panicked at input/code.rs:39:31:
index out of bounds: the len is 200 but the index is 201
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Test 8

Verdict: RUNTIME ERROR

thread 'main' panicked at input/code.rs:39:31:
index out of bounds: the len is 200 but the index is 201
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Test 9

Verdict: RUNTIME ERROR

thread 'main' panicked at input/code.rs:39:31:
index out of bounds: the len is 1000 but the index is 1001
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Test 10

Verdict: RUNTIME ERROR

thread 'main' panicked at input/code.rs:39:31:
index out of bounds: the len is 1000 but the index is 1001
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER