UVA - 669 Defragment

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 <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <stack>
using namespace std;
const int MAXN = 10005;

int culsters[MAXN];
int culster_num, file_num;
int cnt,num;
stack<int> 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;
}

UVA - 669 Defragment