题意：简单说就是将第i个簇号放回i,求最少的步数

思路：只处理链形，和环形的情况，其他的可以不管，对于链形来说，只要倒置就行了，环形的找一个空闲的放一个，然后就是链形的情况了

#include 
  
   
#include 
   
     #include 
    
      #include 
     
       #include 
      
        using namespace std; const int MAXN = 10005; int culsters[MAXN]; int culster_num, file_num; int cnt,num; stack
       
         s; void cal() { int next; for (int i = 1; i <= culster_num; i++) { if (culsters[i] == i) continue; else if (culsters[i] != 0) { s.push(i); next = culsters[i]; int is_circle = 0; while (1) { if (culsters[next] == i) { is_circle = 1; break; } else if (culsters[next] == 0) { is_circle = 0; break; } s.push(next); next = culsters[next]; } int t, j; if (is_circle == 1) { for (j = culster_num; j >= 1; j--) if (culsters[j] == 0) break; printf("%d %d\n", next, j); culsters[j] = culsters[next]; while (!s.empty()) { t = s.top(); printf("%d %d\n", t, next); culsters[next] = culsters[t]; next = t; s.pop(); num++; } culsters[next] = culsters[j]; culsters[j] = 0; printf("%d %d\n", j, next); } else { while (!s.empty()) { t = s.top(); printf("%d %d\n", t, next); culsters[next] = culsters[t]; next = t; s.pop(); num++; } culsters[next] = 0; } } } if (num == 0) printf("No optimization needed\n"); } int main() { int t; scanf("%d", &t); while (t--) { scanf("%d%d", &culster_num, &file_num); memset(culsters, 0, sizeof(culsters)); cnt = 1, num = 0; for (int i = 0; i < file_num; i++) { int n, t; scanf("%d", &n); for (int j = 0; j < n; j++) { scanf("%d", &t); culsters[t] = cnt++; } } cal(); if (t) printf("\n"); } return 0; }