题解移步至：http://blog.csdn.net/huzecong/article/details/12174359 （斜眼笑）
A:
1 #include<cstdio>
2 #include<cstdlib>
3 #include<cstring>
4
5 using namespace std;
6
7 int n;
8
9 int main()
10 {
11 scanf("%d",&n);
12 int max=0;
13 long long sum=0;
14 for (int a=1;a<=n;a++)
15 {
16 int v;
17 scanf("%d",&v);
18 if (v>max) max=v;
19 sum+=v;
20 }
21 sum=(sum-1)/(n-1)+1;
22 if (sum>max) printf("%I64d
",sum);
23 else printf("%d
",max);
24
25 return 0;
26 }
B:
1 #include<cstdio>
2 #include<cstdlib>
3 #include<cstring>
4 #include<algorithm>
5
6 using namespace std;
7
8 const int maxn=100010;
9 const long long INF=100000000000000ll;
10
11 int n,en,q[maxn],f[maxn];
12
13 long long z[maxn],minv[maxn],least[maxn];
14
15 struct edge
16 {
17 int e;
18 edge *next;
19 }*v[maxn],ed[maxn<<1];
20
21 void add_edge(int s,int e)
22 {
23 en++;
24 ed[en].next=v[s];v[s]=ed+en;v[s]->e=e;
25 }
26
27 long long gcd(long long a,long long b)
28 {
29 if (!b) return a;
30 else return gcd(b,a%b);
31 }
32
33 int main()
34 {
35 scanf("%d",&n);
36 long long ans=0;
37 for (int a=1;a<=n;a++)
38 scanf("%I64d",&z[a]),ans+=z[a];
39 for (int a=1;a<n;a++)
40 {
41 int s,e;
42 scanf("%d%d",&s,&e);
43 add_edge(s,e);
44 add_edge(e,s);
45 }
46 int front=1,tail=1;
47 q[1]=1;
48 for (;front<=tail;)
49 {
50 int now=q[front++];
51 for (edge *e=v[now];e;e=e->next)
52 if (e->e!=1 && !f[e->e])
53 {
54 f[e->e]=now;
55 q[++tail]=e->e;
56 }
57 }
58 for (int a=n;a>=1;a--)
59 {
60 int now=q[a];
61 minv[now]=INF;
62 least[now]=1;
63 int tot=0;
64 for (edge *e=v[now];e;e=e->next)
65 if (e->e!=f[now])
66 {
67 tot++;
68 minv[now]=min(minv[now],minv[e->e]*least[e->e]);
69 least[now]=least[now]/gcd(least[now],least[e->e])*least[e->e];
70 }
71 if (!tot)
72 {
73 minv[now]=z[now];
74 continue;
75 }
76 if (least[now]) minv[now]=minv[now]/least[now];
77 else minv[now]=0;
78 least[now]*=tot;
79 }
80 printf("%I64d
",ans-least[1]*minv[1]);
81
82 return 0;
83 }
C:
1 #include<cstdio>
2 #include<cstdlib>
3 #include<cstring>
4 #include<cmath>
5 #include<algorithm>
6 #include<vector>
7
8 using namespace std;
9
10 const int maxn=100010;
11 const int maxs=350;
12
13 int n,m,q,delta[maxn][maxs],num[maxn],to[maxn];
14
15 long long z[maxn],res[maxs],col[maxs];
16
17 bool use[maxs][maxn];
18
19 char s[4];
20
21 vector<int> y[maxn];
22
23 int main()
24 {
25 scanf("%d%d%d",&n,&m,&q);
26 for (int a=1;a<=n;a++)
27 scanf("%I64d",&z[a]);
28 int limit=0;
29 for (int a=1;a<=m;a++)
30 {
31 scanf("%d",&num[a]);
32 for (int b=1;b<=num[a];b++)
33 {
34 int v;
35 scanf("%d",&v);
36 y[a].push_back(v);
37 }
38 limit+=num[a];
39 }
40 limit=(int)(sqrt(limit));
41 int cnt=0;
42 for (int a=1;a<=m;a++)
43 if (num[a]>limit)
44 {
45 to[a]=++cnt;
46 for (int b=0;b<num[a];b++)
47 use[cnt][y[a][b]]=true,res[cnt]+=z[y[a][b]];
48 }
49 for (int a=1;a<=m;a++)
50 for (int b=1;b<=cnt;b++)
51 for (int c=0;c<num[a];c++)
52 delta[a][b]+=use[b][y[a][c]];
53 for (int a=1;a<=q;a++)
54 {
55 scanf("%s",s);
56 if (s[0]=='?')
57 {
58 int p;
59 scanf("%d",&p);
60 long long ans=0;
61 if (num[p]<=limit)
62 {
63 for (int b=0;b<num[p];b++)
64 ans+=z[y[p][b]];
65 for (int b=1;b<=cnt;b++)
66 ans+=col[b]*delta[p][b];
67 }
68 else
69 {
70 ans=res[to[p]];
71 for (int b=1;b<=cnt;b++)
72 ans+=col[b]*delta[p][b];
73 }
74 printf("%I64d
",ans);
75 }
76 else
77 {
78 int p,x;
79 scanf("%d%d",&p,&x);
80 if (num[p]<=limit)
81 {
82 for (int b=0;b<num[p];b++)
83 z[y[p][b]]+=x;
84 for (int b=1;b<=cnt;b++)
85 res[b]+=(long long)x*delta[p][b];
86 }
87 else col[to[p]]+=x;
88 }
89 }
90
91 return 0;
92 }
D:
1 #include<cstdio>
2 #include<cstdlib>
3 #include<cstring>
4
5 using namespace std;
6
7 #define inc(a,b) {a+=b;if (a>=mo) a-=mo;}
8
9 const int maxn=3010;
10 const int mo=1000000007;
11
12 int n,m,f[maxn][maxn];
13
14 char s[maxn][maxn];
15
16 int solve(int x1,int y1,int x2,int y2)
17 {
18 memset(f,0,sizeof(f));
19 f[x1][y1]=1;
20 for (int a=x1;a<=x2;a++)
21 for (int b=y1;b<=y2;b++)
22 if (s[a][b]=='.')
23 {
24 inc(f[a+1][b],f[a][b]);
25 inc(f[a][b+1],f[a][b]);
26 }
27 else f[a][b]=0;
28 return f[x2][y2];
29 }
30
31 int main()
32 {
33 scanf("%d%d",&n,&m);
34 for (int a=1;a<=n;a++)
35 scanf("%s",s[a]+1);
36 printf("%d
",(int)((((long long)solve(1,2,n-1,m)*solve(2,1,n,m-1)-(long long)solve(1,2,n,m-1)*solve(2,1,n-1,m))%mo+mo)%mo));
37
38 return 0;
39 }