HDOJ 4496 D-City(並查集變形，逆序 刪邊)
阿新 • • 發佈：2019-02-20
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.
D-City
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65535/65535 K (Java/Others)
Total Submission(s): 2656 Accepted Submission(s): 928
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.
#include<cstdio>
#include<cstring>
#define max 100010
int set[10010],count;
int ans[max],x[max],y[max];
int find(int x)
{
int r=x;
int t;
while(r!=set[r])
r=set[r];
while(r!=x)
{
t=set[x];
set[x]=r;
x=t;
}
return r;
}
void merge(int a,int b,int k)
{
int fa=find(a);
int fb=find(b);
if(fa!=fb)
{
count--;//連通之前沒有連通地區後
set[fa]=fb;
}
ans[k]=count;
}
int main()
{
int n,m,i;
while(scanf("%d%d",&n,&m)!=EOF)
{
for(i=0;i<n;++i)
set[i]=i;
for(i=0;i<m;++i)
scanf("%d%d",&x[i],&y[i]);
ans[m]=n;
count=n;
for(i=m-1;i>0;i--)
merge(x[i],y[i],i);
for(i=1;i<=m;++i)
printf("%d\n",ans[i]);
}
return 0;
}