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[100000];
    while(scanf("%d",&n)!=EOF)
    {
        

        int tem,i,left;
        left = n-1;
        for(i=0;i<n;i++)
        {
            scanf("%d",&tem);
            loc[tem] = i;
            if(tem == i && i!=0)
                --left;
        }

        int count = 0;
        int k = 1;
        while(left > 0)
        {
            if(loc[0]==0)
            {
               while(k < n)
               {
                  if( loc[k] != k )
                  {
                      swap(loc[0],loc[k]);
                      ++count;
                      break;
                  }
                  ++k;
               }
            }


            while(loc[0]!=0)
            {
                swap(loc[0],loc[loc[0]]);
                ++count;
                --left;
            }

        }

        printf("%d
",count);
    }
    return 0;
}