C++ 代码

#include <iostream>
#include <algorithm>
using namespace std;

const int MAX_N = 100010;
int arr[MAX_N];
int main() {
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> arr[i];
    }
    int sum = 0;
    for (int i = 0; i < n; i++) {
        int cnt = 0;
        //交换到正确位置为止
        while (arr[i] != i) {
            swap(arr[i], arr[arr[i]]);
            cnt++;
        }
        if (cnt > 0) {
            //如果不在0位置交换，需要借助0多交换2次
            if (i) cnt += 2;
            sum += cnt;
        }
    }
    printf("%d\n", sum);
    return 0;
}