PAT甲级——A1067 Sort with Swap(0, i)

Given any permutation of the numbers {0, 1, 2,..., N−1}, it is easy to sort them in increasing order. But what if Swap(0, *) is the ONLY operation that is allowed to use? For example, to sort {4, 0, 2, 1, 3} we may apply the swap operations in the following way:

Swap(0, 1) => {4, 1, 2, 0, 3}
Swap(0, 3) => {4, 1, 2, 3, 0}
Swap(0, 4) => {0, 1, 2, 3, 4}

Now you are asked to find the minimum number of swaps need to sort the given permutation of the first Nnonnegative integers.

Input Specification:

Each input file contains one test case, which gives a positive N (≤) followed by a permutation sequence of {0, 1, ..., N−1}. All the numbers in a line are separated by a space.

Output Specification:

For each case, simply print in a line the minimum number of swaps need to sort the given permutation.

Sample Input:

10
3 5 7 2 6 4 9 0 8 1

Sample Output:

9

#include <iostream>
using namespace std;
int m = 0, N, nums[100005], flag = 1, index = 1;
int main()
{
    cin >> N;
    for (int i = 0; i < N; ++i)
        cin >> nums[i];

    while (index<N)
    {
        while (nums[0] != 0)
        {
            swap(nums[0], nums[nums[0]]);
            ++m;
        }
        for (; index < N; ++index)//使用index，不用每次从0开始遍历
        {
            if (index != nums[index])
            {
                swap(nums[0], nums[index]);
                ++m;
                break;
            }
        }        
    }
    cout << m << endl;
    return 0;
}