Portal
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)
Total Submission(s): 977 Accepted Submission(s): 490
Problem Description
ZLGG found a magic theory that the bigger banana the bigger banana peel .This important theory can help him make a portal in our universal. Unfortunately, making a pair of portals will cost min{T} energies. T in a path between point V and point U is the length of the longest edge in the path. There may be lots of paths between two points. Now ZLGG owned L energies and he want to know how many kind of path he could make.
Input
There are multiple test cases. The first line of input contains three integer N, M and Q (1 < N ≤ 10,000, 0 < M ≤ 50,000, 0 < Q ≤ 10,000). N is the number of points, M is the number of edges and Q is the number of queries. Each of the next M lines contains three integers a, b, and c (1 ≤ a, b ≤ N, 0 ≤ c ≤ 10^8) describing an edge connecting the point a and b with cost c. Each of the following Q lines contain a single integer L (0 ≤ L ≤ 10^8).
Output
Output the answer to each query on a separate line.
Sample Input
10 10 10
7 2 1
6 8 3
4 5 8
5 8 2
2 8 9
6 4 5
2 1 5
8 10 5
7 3 7
7 8 8
10
6
1
5
9
1
8
2
7
6
Sample Output
36
13
1
13
36
1
36
2
16
13
这题挺不错的,学到了离线算法。题目要求两点之间最大边的最小值小于某值的个数。其实就是求点对。
集合划分
#include<iostream> #include<cstdio> #include<cstring> #include<cmath> #include<string> #include<algorithm> #include<cstdlib> using namespace std; int n,m,q,set[50010],num[50010],ans[50010]; struct node { int x,y,w; }e[50010]; struct nod { int x,id; }aa[50010]; bool cmp(node a,node b) { return a.w<b.w; } bool cmp1(nod a,nod b) { return a.x<b.x; } int find(int x) { if(x!=set[x]) set[x]=find(set[x]); return set[x]; } int Union(int a,int b) { int fx,fy; fx=find(a),fy=find(b); if(fx==fy) return 0; int t=num[fx]*num[fy]; num[fx]+=num[fy]; num[fy]=0; set[fy]=fx; return t; } int main() { while(scanf("%d%d%d",&n,&m,&q)!=EOF) { memset(e,0,sizeof(e)); memset(ans,0,sizeof(ans)); for(int i=1;i<=n;i++) set[i]=i,num[i]=1; for(int i=1;i<=m;i++) { scanf("%d%d%d",&e[i].x,&e[i].y,&e[i].w); } sort(e+1,e+1+m,cmp); for(int i=1;i<=q;i++) { scanf("%d",&aa[i].x); aa[i].id=i; } sort(aa+1,aa+1+q,cmp1); int k=1,cnt=0; for(int i=1;i<=q;i++) { while(k<=m&&e[k].w<=aa[i].x) { cnt+=Union(e[k].x,e[k].y); k++; } ans[aa[i].id]=cnt; } for(int i=1;i<=q;i++) printf("%d\n",ans[i]); } return 0; }