http://codeforces.com/contest/489/problem/A
看样例不难发现，对于i，找到 i<=j<=n-1里最小的数，若有与i交换
1 public static void main(String[] args) {
2 Scanner io = new Scanner(System.in);
3 int n = io.nextInt();
4 int[] a = new int[n];
5 for (int i = 0; i < n; i++) a[i] = io.nextInt();
6 int ans = 0;
7 ArrayList<int[]> ans2 = new ArrayList<>();
8 for (int i = 0; i < n; i++){
9 int min=a[i],index=-1;
10 for (int j = i + 1; j < n; j++) if (a[j]<min){min=a[j];index=j;}
11 if (index!=-1){
12 ans++;
13 ans2.add(new int[]{i,index});
14 int t=a[i];a[i]=a[index];a[index]=t;
15 }
16 }
17 System.out.println(ans);
18 for (int[] aa : ans2) System.out.println(aa[0] + " " + aa[1]);
19 }