97
最大流-hdoj-1532
hdoj-1532-Drainage Ditches
Problem 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 a while and takes quite along 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
5 4
1 2 40
1 4 20
2 4 20
2 3 30
3 4 10
Sample Output
50
大意：為防止三葉草被淹，挖溝散水。求最大流。以示例輸入進行說明。5為邊數，4為頂點數。頂點編號從1開始。1為源點，4為匯點。接下來的5行，Si Ei Ci:水從Si流向Ei，最大流量為Ci。隻能單向流哦。
最後更新：2017-04-03 12:56:05