FASTFLOW - Fast Maximum Flow
Given a graph with N (2 ≤ N ≤ 5,000) vertices numbered 1 to N and M (1 ≤ M ≤ 30,000) undirected, weighted edges, compute the maximum flow / minimum cut from vertex 1 to vertex N.
Input
The first line contains the two integers N and M. The next M lines each contain three integers A, B, and C, denoting that there is an edge of capacity C (1 ≤ C ≤ 109) between nodes A and B (1 ≤ A, B ≤ N). Note that it is possible for there to be duplicate edges, as well as an edge from a node to itself.
Output
Print a single integer (which may not fit into a 32-bit integer) denoting the maximum flow / minimum cut between 1 and N.
Example
Input: 4 6 1 2 3 2 3 4 3 1 2 2 2 5 3 4 3 4 3 3 Output: 5
Viewing the problem as max-flow, we may send 3 units of flow through the path 1 - 2 - 3 - 4 and 2 units of flow through the path 1 - 3 - 4. Viewing the problem as min-cut, we may cut the first and third edges. Either way the total is 5.
Note: see also http://www.spoj.com/problems/MATCHING/.
hide comments
sigma_poet:
2016-01-10 05:57:59
Dinic 's time is O(N^2*M), but N is 5000 and M is 30000. Will it get a pass ??? I'm not sure. |
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Dario Pavlovic:
2015-07-30 17:04:32
yup, a well written dinic works. |
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dfranzen:
2015-07-14 01:01:59
dinic's algorithm works ;) Last edit: 2015-07-14 01:09:48 |
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(Tjandra Satria Gunawan)(曾毅昆):
2015-05-28 16:35:09
very fun! among 931 accepted users (for now), only 10 of them using pure C language ;-) |
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dened:
2015-01-22 09:17:23
My solution using highest-label push-relabel algorithm was accepted even without any heuristics. But I had to implement an efficient data structure for the sparse graph. |
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Reza:
2014-12-23 13:41:26
Dinic --> Accepted. trust me :-" |
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Anuj Arora:
2014-11-30 20:54:09
Very hard problem.......too many TLE......phewww |
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Luis Manuel D�az Bar�n:
2014-08-12 16:39:25
Edmonds-Karp TLE on test 11. It should be allowed to pass Last edit: 2014-08-25 17:34:51 |
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rahul kumar:
2014-08-07 20:56:07
can anybody tell me why im getting WA on 12th test |
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Anmol Pandey:
2014-07-15 13:37:33
Edmond-Karps algo gives TLE Last edit: 2014-07-15 13:38:40 |
Added by: | Neal Wu |
Date: | 2009-03-25 |
Time limit: | 2s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ERL JS-RHINO |