POJ 3177
POJ 3177
题目大意：同poj 3352。
解：同poj3352，但记得处理重边的问题。
View Code
1 //poj 3177
2 const
3 maxn=5111;
4 maxm=11111;
5 type
6 data=record
7 dest, next, op: longint;
8 end;
9 var
10 edge: array[1..maxm*2]of data;
11 pre, dfn, low, deg, vect: array[1..maxn]of longint;
12 g: array[1..maxn, 1..maxn]of boolean;
13 visit:array[1..maxn]of boolean;
14 n, m, time, tot, ans: longint;
15 procedure add(x, y: longint);
16 begin
17 inc(tot);
18 with edge[tot] do begin
19 dest := y;
20 next := vect[x];
21 vect[x] := tot;
22 op := tot + 1;
23 end;
24 inc(tot);
25 with edge[tot] do begin
26 dest := x;
27 next := vect[y];
28 vect[y] := tot;
29 op := tot - 1;
30 end;
31 end;
32
33 procedure init;
34 var
35 i, x, y: longint;
36 begin
37 tot := 0; ans := 0;
38 fillchar(vect, sizeof(vect), 0);
39 fillchar(g, sizeof(g), 0);
40 readln(n, m);
41 for i := 1 to m do begin
42 readln(x, y);
43 if not g[x, y] then begin
44 add(x, y);
45 g[x, y] := true;
46 g[y, x] := true;
47 end;
48 end;
49 end;
50
51 procedure tarjan(x: longint);
52 var
53 i: longint;
54 begin
55 inc(time);
56 dfn[x] := time; low[x] := time;
57 visit[x] := true;
58 i := vect[x];
59 while i<>0 do
60 with edge[i] do begin
61 if (pre[x]<>dest) then
62 if (dfn[dest]=0) then begin
63 pre[dest] := x;
64 tarjan(dest);
65 pre[dest] := 0;
66 if (low[dest]<low[x]) then low[x] := low[dest];
67 end
68 else if visit[dest] then begin
69 if (dfn[dest]<low[x]) then low[x] := dfn[dest];
70 end;
71 i := next;
72 end;
73 visit[x] := false;
74 end;
75
76 procedure main;
77 var
78 i, u: longint;
79 begin
80 fillchar(dfn, sizeof(dfn), 0);
81 fillchar(pre, sizeof(pre), 0);
82 fillchar(visit, sizeof(visit), 0);
83 time := 0;
84 for i := 1 to n do if dfn[i]=0 then tarjan(i);
85 fillchar(deg, sizeof(deg), 0);
86 for u := 1 to n do begin
87 i := vect[u];
88 while i<>0 do
89 with edge[i] do begin
90 if (low[u]<>low[dest]) then begin
91 inc(deg[low[u]]);
92 inc(deg[low[dest]]);
93 end;
94 i := next;
95 end;
96 end;
97 for i := 1 to time do
98 if deg[i] >> 1 = 1 then inc(ans);
99 if ans = 1 then ans := 0;
100 ans := (ans + 1) >> 1;
101 end;
102
103 procedure print;
104 begin
105 writeln(ans);
106 end;
107
108 begin
109 assign(input,'1.txt'); reset(input);
110 while not seekeof do begin
111 init;
112 main;
113 print;
114 end;
115 end.
