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

 1 #include <iostream>
 2 using namespace std;
 5 int m = 0, N, nums[100005], flag = 1, index = 1;
 6 int main()
 7 {
 8     cin >> N;
 9     for (int i = 0; i < N; ++i)
10         cin >> nums[i];
11 
12     while (index<N)
13     {
14         while (nums[0] != 0 )
 15          {
 16              the swap (the nums [ 0 ], the nums [the nums [ 0 ]]);
 . 17              ++ m;
 18 is          }
 . 19          for (; index <N; index ++) // use index, not every 0 start traversing 
20 is          {
 21 is              IF (index =! the nums [index])
 22 is              {
 23 is                  the swap (the nums [ 0 ], the nums [index]);
 24                  ++ m;
 25                  BREAK ;
 26 is              }
 27          }        
28     }
29     cout << m << endl;
30     return 0;
31 }