poj1741，POJ1273 裸裸的網絡流-技術動態-匯編語言學習筆記

poj1741，POJ1273 裸裸的網絡流

2023-10-18 阅读 26 评论 0

摘要：北京好熱啊，宿舍還沒空調，都不能安安靜靜地敲代碼了~>_<~今天老師講網絡流完全沒聽啊，晚上想了好久的網絡流，感覺還是沒有完全理解，過了一道模板題。 ? Drainage Ditches ? Time Limit:?1000MS?Memory Limit:?10000KTotal Submissio

北京好熱啊，宿舍還沒空調，都不能安安靜靜地敲代碼了~>_<~今天老師講網絡流完全沒聽啊，晚上想了好久的網絡流，感覺還是沒有完全理解，過了一道模板題。

Drainage Ditches

Time Limit:?1000MS	?	Memory Limit:?10000K
Total Submissions:?61994	?	Accepted:?23794

Description

Every time it rains on Farmer John's fields, a pond forms over Bessie's favorite clover patch. This means that the clover is covered by water for awhile and takes quite a long time to regrow. Thus, Farmer John has built a set of drainage ditches so that Bessie's clover patch is never covered in water. Instead, the water is drained to a nearby stream. Being an ace engineer, Farmer John has also installed regulators at the beginning of each ditch, so he can control at what rate water flows into that ditch.?
Farmer John knows not only how many gallons of water each ditch can transport per minute but also the exact layout of the ditches, which feed out of the pond and into each other and stream in a potentially complex network.?
Given all this information, determine the maximum rate at which water can be transported out of the pond and into the stream. For any given ditch, water flows in only one direction, but there might be a way that water can flow in a circle.?

Input

The input includes several cases.?For each case, the first line contains two space-separated integers, N (0 <= N <= 200) and M (2 <= M <= 200). N is the number of ditches that Farmer John has dug. M is the number of intersections points for those ditches. Intersection 1 is the pond. Intersection point M is the stream. Each of the following N lines contains three integers, Si, Ei, and Ci. Si and Ei (1 <= Si, Ei <= M) designate the intersections between which this ditch flows. Water will flow through this ditch from Si to Ei. Ci (0 <= Ci <= 10,000,000) is the maximum rate at which water will flow through the ditch.

Output

For each case, output a single integer, the maximum rate at which water may emptied from the pond.

Sample Input

Sample Output

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<algorithm>
 5 #include<queue>
 6 using namespace std;
 7 int map[300][300];
 8 int pre[300];
 9 bool vis[300];
10 int n,m,s,t;
11 bool bfs()
12 {
13     int i,temp;
14     queue<int>q;
15     memset(pre,0,sizeof(pre));
16     memset(vis,0,sizeof(vis));
17     vis[s]=true;
18     q.push(s);
19     while(!q.empty())
20     {
21         temp=q.front();
22         q.pop();
23         if(temp==t) return true;
24         for(i=1;i<=n;i++)
25         {
26             if(!vis[i]&&map[temp][i])
27             {
28                 q.push(i);
29                 pre[i]=temp;
30                 vis[i]=true;
31             }
32         }
33     }
34     return false;
35 }
36 int EK()
37 {
38     int i,ans=0;
39     while(1)
40     {
41         if(!bfs()) return ans;
42         int MIN=9999999;
43         for(i=t;i!=s;i=pre[i])
44             MIN=min(MIN,map[pre[i]][i]);
45         for(i=t;i!=s;i=pre[i])
46         {
47             map[pre[i]][i]-=MIN;
48             map[i][pre[i]]+=MIN;
49         }
50         ans+=MIN;
51     }
52 }
53 int main()
54 {
55     while(~scanf("%d%d",&m,&n))
56     {
57         s=1,t=n;
58         memset(map,0,sizeof(map));
59         for(int i=0;i<m;i++)
60         {
61             int a,b,c;
62             scanf("%d%d%d",&a,&b,&c);
63             map[a][b]+=c;
64         }
65         printf("%d\n",EK());
66     }
67     return 0;
68 }

View Code

轉載于:https://www.cnblogs.com/zero-zz/p/4684435.html

原文链接：https://hbdhgg.com/4/147338.html

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