Problem Description
Luxer is a really bad guy. He destroys everything he met.
One day Luxer went to D-city. D-city has N D-points and M D-lines. Each D-line connects exactly two D-points. Luxer will destroy all the D-lines. The mayor of D-city wants to know how many connected blocks of D-city left after Luxer destroying the first K D-lines in the input.
Two points are in the same connected blocks if and only if they connect to each other directly or indirectly.
Input
First line of the input contains two integers N and M.
Then following M lines each containing 2 space-separated integers u and v, which denotes an D-line.
Constraints:
0 < N <= 10000
0 < M <= 100000
0 <= u, v < N.
Output
Output M lines, the ith line is the answer after deleting the first i edges in the input.
Sample Input
5 10 0 1 1 2 1 3 1 4 0 2 2 3 0 4 0 3 3 4 2 4
Sample Output
1 1 1 2 2 2 2 3 4 5
Hint
The graph given in sample input is a complete graph, that each pair of vertex has an edge connecting them, so there's only 1 connected block at first. The first 3 lines of output are 1s because after deleting the first 3 edges of the graph, all vertexes still connected together. But after deleting the first 4 edges of the graph, vertex 1 will be disconnected with other vertex, and it became an independent connected block. Continue deleting edges the disconnected blocks increased and finally it will became the number of vertex, so the last output should always be N.
题意是有n个点，m条边，刚开始这些边都是连着的，然后按顺序逐一破坏这些边，然后让你输出每破坏一次图中还剩几个集合，刚开始肯定是有一个集合的，最后都破坏完了就是n个集合了。
思路：反向考虑，正向删边化为反向加边，利用并查集，每次加边后联通块数减1
#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
#define maxn 100005
struct edge
{
int x,y;
}edge[maxn];
int father[maxn];
int ans[maxn];
int n,m,sum;
void init()
{
for(int i=0;i<n;i++)
father[i]=i;
}
int find(int x){
if(father[x]!=x)
father[x]=find(father[])
}
void unoin(int x,int y)
{
int r1=find(x);
int r2=find(y);
if(r1!=r2)
{father[r2]=r1;
sum--;
}
}
int main()
{while(~scanf("%d%d",&n,&m))
{
init();
memset(ans,0,sizeof(ans));
sum=n;
for(int i=0;i<m;i++)
scanf("%d%d",&edge[i].x,&edge[i].y);
for(int i=m-1;i>=0;i--)
{
ans[i]=sum;
unoin(edge[i].x,edge[i].y);
}
for(int i=0;i<m;i++)
printf("%d\n",ans[i]);
}
return 0;
}