D-City
Time Limit: 1000ms
Memory Limit: 65535KB
This problem will be judged on HDU. Original ID: 4496
64-bit integer IO format: %I64d Java class name: Main
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.
Source
解题：并查集，逆向求解。。。
1 #include <iostream>
2 #include <cstdio>
3 #include <cstring>
4 #include <cmath>
5 #include <algorithm>
6 #include <climits>
7 #include <vector>
8 #include <queue>
9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define INF 0x3f3f3f3f
15 using namespace std;
16 const int maxn = 10010;
17 int uf[maxn],n,m;
18 int ans[maxn*10];
19 int a[maxn*10],b[maxn*10];
20 int Find(int x){
21 if(x != uf[x])
22 uf[x] = Find(uf[x]);
23 return uf[x];
24 }
25 int main(){
26 int i,j,k;
27 while(~scanf("%d %d",&n,&m)){
28 for(i = 0; i <= n; i++)
29 uf[i] = i;
30 for(i = 1; i <= m; i++){
31 scanf("%d %d",a+i,b+i);
32 }
33 ans[m] = n;
34 for(i = m; i; i--){
35 int tx= Find(a[i]);
36 int ty = Find(b[i]);
37 uf[tx] = ty;
38 if(tx != ty){
39 ans[i-1] = ans[i]-1;
40 }else ans[i-1] = ans[i];
41 }
42 for(i = 1; i <= m; i++){
43 printf("%d\n",ans[i]);
44 }
45 }
46 return 0;
47 }
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