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

时间限制

150 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

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 N nonnegative integers.

Input Specification:

Each input file contains one test case, which gives a positive N (<=10⁵) 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 <stdio.h>
 #include<algorithm>
 using namespace std;
 int main()
 {
     int n;
     int loc[];
     while(scanf("%d",&n)!=EOF)
     {

         int tem,i,left;
         left = n-;
         for(i=;i<n;i++)
         {
             scanf("%d",&tem);
             loc[tem] = i;
             if(tem == i && i!=)
                 --left;
         }

         int count = ;
         int k = ;
         while(left > )
         {
             if(loc[]==)
             {
                while(k < n)
                {
                   if( loc[k] != k )
                   {
                       swap(loc[],loc[k]);
                       ++count;
                       break;
                   }
                   ++k;
                }
             }

             while(loc[]!=)
             {
                 swap(loc[],loc[loc[]]);
                 ++count;
                 --left;
             }

         }

         printf("%d\n",count);
     }
     return ;
 }