poj 3140 Contestants Division

http://poj.org/problem?id=3140

这道题数据大，需要用long long，dfs枚举删除的边求最小就行。

 1 #include <cstdio>

 2 #include <vector>

 3 #include <cstring>

 4 #include <algorithm>

 5 #define ll long long

 6 #define maxn 200000

 7 using namespace std;

 8 const ll inf=99999999999999999ll;

 9 

10 ll a[maxn];

11 ll total;

12 ll min1;

13 int n,m;

14 vector<int>q[maxn];

15 bool vis[maxn];

16 ll ABS(ll a)

17 {

18     if(a<0) return -a;

19     return a;

20 }

21 

22 ll min2(ll a,ll b)

23 {

24     if(a>b) return b;

25     return a;

26 }

27 

28 ll dfs(int num)

29 {

30     vis[num]=true;

31     ll ans=a[num];

32     for(int i=0; i<(int)q[num].size(); i++)

33     {

34         int to=q[num][i];

35         if(!vis[to])

36         {

37           ans+=dfs(to);

38         }

39     }

40     min1=min2(min1,ABS(total-ans-ans));

41     return ans;

42 }

43 

44 int main()

45 {

46     int case1=0;

47     while(scanf("%d%d",&n,&m)!=EOF)

48     {

49         min1=inf;

50         if(n==0&&m==0) break;

51         memset(a,0,sizeof(a));

52         memset(vis,false,sizeof(vis));

53         total=0;

54         for(int i=0; i<=n; i++)

55         {

56             q[i].clear();

57         }

58         for(int i=1; i<=n; i++)

59         {

60             scanf("%lld",&a[i]);

61             total+=a[i];

62         }

63         for(int i=1; i<=m; i++)

64         {

65             int x,y;

66             scanf("%d%d",&x,&y);

67             q[x].push_back(y);

68             q[y].push_back(x);

69         }

70         dfs(1);

71         printf("Case %d: %lld\n",++case1,min1);

72     }

73     return 0;

74 }

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