网络流网络流1532Drainage DitchesTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 9885 Accepted Submission(s): 4695Problem DescriptionEvery 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.InputThe 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.OutputFor each case, output a single integer, the maximum rate at which water may emptied from the pond.Sample Input 5 41 2 401 4 202 4 202 3 303 4 10 Sample Output 50Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 5849 Accepted Submission(s): 2225Problem Description给你一个n*n的格子的棋盘，每个格子里面有一个非负数。
从中取出若干个数，使得任意的两个数所在的格子没有公共边，就是说所取的数所在的2个格子不能相邻，并且取出的数的和最大。
Input包括多个测试实例，每个测试实例包括一个整数n 和n*n个非负数(n<=20)Output对于每个测试实例，输出可能取得的最大的和Sample Input375 15 2175 15 2834 70 5Sample Output188Time Limit: 10000/5000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 4786 Accepted Submission(s): 1505Problem Description给你一个m*n的格子的棋盘，每个格子里面有一个非负数。
从中取出若干个数，使得任意的两个数所在的格子没有公共边，就是说所取数所在的2个格子不能相邻，并且取出的数的和最大。
Input包括多个测试实例，每个测试实例包括2整数m,n和m*n个非负数(m<=50,n<=50) Output对于每个测试实例，输出可能取得的最大的和Sample Input3 375 15 2175 15 2834 70 5Sample Output1881733EscapeTime Limit: 1000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 1175 Accepted Submission(s): 328Problem DescriptionLoneknight hates attending class very much. Every time he is attending class, when he feel tiresome with the class, he start planning the shortest path he can escape from the classroom. Therefore, he can escape from classroom so quickly that he is always the first one escape from the classroom after the class finishes. He is very proud of this fact.One day, loneknight is day dreaming in class, and planning the shortest path for escaping. Suddently, an issue come into his mind, if everyone in the classroom want to escape as soon as possible just as loneknight, what will happend? As a kind man, loneknight want to plan a strategy that will let everyone escape from the classroom with minimum time consume. But after dozens of minutes of consideration, loneknight find this problem so difficult for him.Now, as the best friend of him, please design a algorithm to solve this problem for him. Note that, at every time unit, everyone can move seperately up, down, left, right one unit, or stay in the old position. In addtion, no one can move to a wall or out of the room, the only way to escape is go through a gate. Moreover, at every time unit, a position can only contain a person, including gates. That means if in time t, a person escape thourgh gate g, no one can go into g in time t, but can go into g in t + 1. Now, it's your job to calculate the minimum time required to escape for everyone.InputThe input consists of several test cases. Each test case start with a line containing two number, n, m (1 < n, m <= 16), the rows and the columns of the room. Then n lines follow, each contain exact m characters, representing th type of unitin it. (. for empty place, X for human, # for wall, @ for gate). Input is end with EOF.OutputYou have to print the shortest time needed for everyone escape from the roomin a single line for each case. (-1 if impossible)Sample Input4 4.@...X..........4 4.@...XX..XX...@.4 4.@...#..#X#..#..Sample Output 12-1。