[POJ 1523]题解
2014-10-14 13:31
113 查看
没什么好说的。。就是YZOI1171..
SPF
Description
Consider the two networks shown below. Assuming that data moves around these networks only between directly connected nodes on a peer-to-peer basis, a failure of a single node, 3, in the network on the left would prevent some of the still available nodes from
communicating with each other. Nodes 1 and 2 could still communicate with each other as could nodes 4 and 5, but communication between any other pairs of nodes would no longer be possible.
Node 3 is therefore a Single Point of Failure (SPF) for this network. Strictly, an SPF will be defined as any node that, if unavailable, would prevent at least one pair of available nodes from being able to communicate on what was previously a fully connected
network. Note that the network on the right has no such node; there is no SPF in the network. At least two machines must fail before there are any pairs of available nodes which cannot communicate.
Input
The input will contain the description of several networks. A network description will consist of pairs of integers, one pair per line, that identify connected nodes. Ordering of the pairs is irrelevant; 1 2 and 2 1 specify the same connection. All node numbers
will range from 1 to 1000. A line containing a single zero ends the list of connected nodes. An empty network description flags the end of the input. Blank lines in the input file should be ignored.
Output
For each network in the input, you will output its number in the file, followed by a list of any SPF nodes that exist.
The first network in the file should be identified as "Network #1", the second as "Network #2", etc. For each SPF node, output a line, formatted as shown in the examples below, that identifies the node and the number of fully connected subnets that remain when
that node fails. If the network has no SPF nodes, simply output the text "No SPF nodes" instead of a list of SPF nodes.
Sample Input
Sample Output
Source
Greater New York 2000
Code:
SPF
Time Limit: 1000MS | Memory Limit: 10000K | |
Total Submissions: 6225 | Accepted: 2863 |
Consider the two networks shown below. Assuming that data moves around these networks only between directly connected nodes on a peer-to-peer basis, a failure of a single node, 3, in the network on the left would prevent some of the still available nodes from
communicating with each other. Nodes 1 and 2 could still communicate with each other as could nodes 4 and 5, but communication between any other pairs of nodes would no longer be possible.
Node 3 is therefore a Single Point of Failure (SPF) for this network. Strictly, an SPF will be defined as any node that, if unavailable, would prevent at least one pair of available nodes from being able to communicate on what was previously a fully connected
network. Note that the network on the right has no such node; there is no SPF in the network. At least two machines must fail before there are any pairs of available nodes which cannot communicate.
Input
The input will contain the description of several networks. A network description will consist of pairs of integers, one pair per line, that identify connected nodes. Ordering of the pairs is irrelevant; 1 2 and 2 1 specify the same connection. All node numbers
will range from 1 to 1000. A line containing a single zero ends the list of connected nodes. An empty network description flags the end of the input. Blank lines in the input file should be ignored.
Output
For each network in the input, you will output its number in the file, followed by a list of any SPF nodes that exist.
The first network in the file should be identified as "Network #1", the second as "Network #2", etc. For each SPF node, output a line, formatted as shown in the examples below, that identifies the node and the number of fully connected subnets that remain when
that node fails. If the network has no SPF nodes, simply output the text "No SPF nodes" instead of a list of SPF nodes.
Sample Input
1 2 5 4 3 1 3 2 3 4 3 5 0 1 2 2 3 3 4 4 5 5 1 0 1 2 2 3 3 4 4 6 6 3 2 5 5 1 0 0
Sample Output
Network #1 SPF node 3 leaves 2 subnets Network #2 No SPF nodes Network #3 SPF node 2 leaves 2 subnets SPF node 3 leaves 2 subnets
Source
Greater New York 2000
Code:
const shuru='test.in'; shuchu='test.out'; maxn=1001; maxm=500001; var ans,dfn,low,headlist:array[0..maxn] of longint; next,t:array[0..maxm] of longint; vis:array[0..maxn] of boolean; pp,tot,x,y,i,j,k,n,m,time,num:longint; sign:boolean; procedure init; begin for i:=1 to 1000 do headlist[i]:=-1; fillchar(vis,sizeof(vis),false); fillchar(ans,sizeof(ans),0); num:=0; while x<>0 do begin readln(y); inc(num); next[num]:=headlist[x]; headlist[x]:=num; t[num]:=y; inc(num); next[num]:=headlist[y]; headlist[y]:=num; t[num]:=x; read(x); end; end; function min(a,b:longint):longint; begin if a<b then exit(a); exit(b); end; procedure dfs(u,fa:longint); var i:longint; begin inc(time); dfn[u]:=time; low[u]:=time; vis[u]:=true; i:=headlist[u]; while i<>-1 do begin if not(vis[t[i]]) then begin dfs(t[i],u); if low[t[i]]>=dfn[u] then inc(ans[u]); low[u]:=min(low[u],low[t[i]]); end else if t[i]<>fa then low[u]:=min(low[u],dfn[t[i]]); i:=next[i]; end; end; procedure main; begin inc(pp); sign:=true; init; ans[1]:=-1; dfs(1,0); writeln('Network #',pp); for i:=1 to maxn do if ans[i]>0 then begin writeln(' SPF node ',i,' leaves ',ans[i]+1,' subnets'); sign:=false; end; if sign then writeln(' No SPF nodes'); writeln; end; begin assign(input,shuru); assign(output,shuchu); reset(input); rewrite(output); read(x); while x<>0 do begin main; read(x); end; end.
相关文章推荐
- poj 1523 SPE
- POJ 1523 SPF(无向图求割点,去割点形成子图数)
- POJ-1523 SPF 割点
- poj1523解题报告
- 【POJ 1523】SPF(割点)
- POJ 1523 SPF tarjan求割点模板
- POJ 1523 SPF //求割点
- poj 1523 SPF (tarjan)
- poj 1523 SPF(tarjan求割点)
- POJ 1523 SPF【割点】
- poj 1523 SPF 无向图求割点
- POJ 1523 Tarjan求割点
- [割点] poj 1523 SPF
- POJ 1523 SPF (割点,连通分量)
- poj 1523 连通基础
- POJ 1523 / ZOJ 1119 - Tarjan算法
- poj1523
- POJ_1523 SPF (Tarjan 求割点)
- poj1523 求割点 tarjan
- poj1523 割点+连通分量