http://www.lydsy.com/JudgeOnline/problem.php?id=2597

in a competetion we offten occur a wins b,b wins c and c wins a,we call this case rock paper scissors given a comptetion graph, mat[i][j]=0 indicate j wins i, mat[i][j]==1 indicate i wins j mat[i][j]==2 indicate i and j are not defined..

you are asked to determine mat[i][j]==2 so that the number of rock paper sissors is maximum

if there is multiple solution output anyone..

http://ideone.com/tN2Gdb

this is my 24 ms AC code, instead of zkw min_cost flow, I use iteration to find unbanlance path, it can run N==1000

complete graph 139ms on codeforces..