Task Schedule
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 6802 Accepted Submission(s): 2124
Problem Description
Our geometry princess XMM has stoped her study in computational geometry to concentrate on her newly opened factory. Her factory has introduced M new machines in order to process the coming N tasks. For the i-th task, the factory has to start processing it at or after day Si, process it for Pi days, and finish the task before or at day Ei. A machine can only work on one task at a time, and each task can be processed by at most one machine at a time. However, a task can be interrupted and processed on different machines on different days.
Now she wonders whether he has a feasible schedule to finish all the tasks in time. She turns to you for help.
Input
On the first line comes an integer T(T<=20), indicating the number of test cases.
You are given two integer N(N<=500) and M(M<=200) on the first line of each test case. Then on each of next N lines are three integers Pi, Si and Ei (1<=Pi, Si, Ei<=500), which have the meaning described in the description. It is guaranteed that in a feasible schedule every task that can be finished will be done before or at its end day.
Output
For each test case, print “Case x: ” first, where x is the case number. If there exists a feasible schedule to finish all the tasks, print “Yes”, otherwise print “No”.
Print a blank line after each test case.
Sample Input
2
4 3
1 3 5
1 1 4
2 3 7
3 5 9
2 2
2 1 3
1 2 2
Sample Output
Case 1: Yes
Case 2: Yes
题意:给N个任务,M台机器。每个任务有最早才能开始做的时间S,deadline E,和持续工作的时间P。每个任务可以分段进行,但是在同一时刻,一台机器最多只能执行一个任务. 问存不存在可行的工作时间。
#include <iostream> #include <cstdio> #include <cstring> #include <cstdlib> #include <cmath> #include <vector> #include <queue> #include <map> #include <algorithm> #include <set> using namespace std; #define MM(a,b) memset(a,b,sizeof(a)) typedef long long ll; typedef unsigned long long ULL; const int mod = 1000000007; const double eps = 1e-10; const int inf = 0x3f3f3f3f; const int big=50000; int max(int a,int b) {return a>b?a:b;}; int min(int a,int b) {return a<b?a:b;}; struct edge{ int to,cap,rev; }; vector<edge> G[1010]; map<string,int> mp; int n,m,k,daymax,level[1010],iter[1010]; int p[1010],s[1010],e[1010],sum; void add_edge(int u,int v,int cap) { G[u].push_back(edge{v,cap,G[v].size()}); G[v].push_back(edge{u,0,G[u].size()-1}); } void bfs(int s) { queue<int> q; q.push(s); level[s]=1; while(q.size()) { int now=q.front();q.pop(); for(int i=0;i<G[now].size();i++) if(G[now][i].cap>0) { edge e=G[now][i]; if(level[e.to]<0) { level[e.to]=level[now]+1; q.push(e.to); } } } } int dfs(int s,int t,int minn) { if(s==t) return minn; for(int &i=iter[s];i<G[s].size();i++) { edge &e=G[s][i]; if(level[e.to]>level[s]&&e.cap>0) { int k=dfs(e.to,t,min(minn,e.cap)); if(k>0) { e.cap-=k; G[e.to][e.rev].cap+=k; return k; } } } return 0; } int max_flow(int s,int t) { int ans=0,temp; for(;;) { memset(level,-1,sizeof(level)); bfs(s); if(level[t]<0) return ans; memset(iter,0,sizeof(iter)); while((temp=dfs(s,t,inf))>0) ans+=temp; } return ans; } void build() { for(int i=0;i<=n+daymax+1;i++) G[i].clear(); for(int i=1;i<=n;i++) add_edge(0,i,p[i]); for(int i=n+1;i<=n+daymax;i++) add_edge(i,n+daymax+1,m); for(int i=1;i<=n;i++) for(int j=1;j<=daymax;j++) if(j>=s[i]&&j<=e[i]) add_edge(i,j+n,1); } int main() { int cas,kk=0; scanf("%d",&cas); while(cas--) { daymax=0;sum=0; scanf("%d %d",&n,&m); for(int i=1;i<=n;i++) { scanf("%d %d %d",&p[i],&s[i],&e[i]); if(e[i]>daymax) daymax=e[i]; sum+=p[i]; } build(); printf("Case %d: ",++kk); if(max_flow(0,n+daymax+1)==sum) printf("Yes\n");//刚开始输出YES,wa了好久,剁手了,以后输出格式都直接粘贴! else printf("No\n"); printf("\n"); } return 0; }
体会建图思想,刚开始我想的是建立一个天数与机器的二元组,然后向汇点连接一条容量为1的边,但是算下来就是会超时了,,因为点太多了,,,其实只要将天数向汇点连接容量为仪器数量的边就好了,这样就控制了仪器的使用数量,然后就是任务向仪器连边,跑跑最大流就可以了