1067. Sort with Swap (0,*) (25)

Given any permutation of the numbers {0, 1, 2,..., N-1}, it's easy-to-sort them in increasing order. What if swaps (0, *) are the only operation and that's allowed to use? For example, to sort {4, 0, 2, 1, 3} We'll apply the swap operations in the following:

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 is asked to find the minimum number of swaps need to sort the given permutation of the first N nonnegative intege Rs.

Input Specification:

Each input file contains one test case, which gives a positive N (<=10^{5) followed by a permutation sequence of {0, 1, ..., N-1}. All the numbers in a line is 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

Source: >  

  
 

   
  

  
#include <iostream>
   
  

  
#include <vector>
   
  

  

   
  

  
using namespace std;
   
  

  

   
  

  
vector<int> num;
   
  

  

   
  

  
int a[100010] = { 0 };
   
  

  
int main(void) {
   
  

  
int n;
   
  

  
cin >> n;
   
  

  
for (int i = 0; i < n; i++) {
   
  

  
int temp;
   
  

  
cin >> temp;
   
  

  
num.push_back(temp);
   
  

  
}
   
  

  

   
  

  
int count = 0;
   
  

  
for (int i = 0; i < n; i++) {
   
  

  
if (num[i] != i)
   
  

  
count++;
   
  

  
else
   
  

  
a[i]++;
   
  

  
}
   
  

  
if (num[0] == 0)
   
  

  
count++;
   
  

  
count--;
   
  

  
a[0] = 1;
   
  

  
int j = 0, p = 0;
   
  

  
int check = 0;
   
  

  
bool flag = false;
   
  

  
for (int q = 0; q < n; q++)
   
  

  
{
   
  

  
while (a[j] == 1) {
   
  

  
j = num[j];
   
  

  
a[j] ++;
   
  

  
}
   
  

  
if (a[q] == 0) {
   
  

  
j = q;
   
  

  
a[j] = 1;
   
  

  
count++;
   
  

  
continue;
   
  

  
}
   
  

  
}
   
  

  

   
  

  

   
  

  
cout << count ;
   
  

  
return 0;
   
  

  
}
  
 

From for notes (Wiz)

1067. Sort with Swap (0,*) (25)