ZOJ 3795:grouping (indent + longest)

http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=5303

Test instructions: There are n person M edge, each side has a u,v, the age of the U is greater than or equal to V, now to divide the n person into x groups, the age of the group can not be directly or indirectly compared, ask at least how many groups can be divided.

Idea: At first did not see test instructions, the direct topological sort did. Later listen to brother said there will be a ring, age is equal to, if there is a ring representing the age of the same, then the ring inside the person is a group, the point after the end of the length of the point is the number of points, and then use DP the longest way to do.

1#include <cstdio>2#include <algorithm>3#include <iostream>4#include <cstring>5#include <string>6#include <cmath>7#include <queue>8#include <vector>9#include <map>Ten#include <Set> One#include <stack> A using namespacestd; - #defineINF 0x3f3f3f3f - #defineN 100010 the structEdge { -     intV, NXT; -} edge[n*3], edg[n*3]; - intCnt[n], dp[n], head[n], hea[n], Tott, tot, Tim, Vis[n], deg[n], dfn[n], low[n], belong[n], num; +stack<int>STA; -  + voidADD (intUintv) { AEDGE[TOT].V = v; EDGE[TOT].NXT = Head[u]; Head[u] = tot++; at } -  - voidAddintUintv) { -EDG[TOTT].V = v; EDG[TOTT].NXT = Hea[u]; Hea[u] = tott++; - } -  in voidTarjan (intu) { -Dfn[u] = Low[u] = + +Tim; toSta.push (U); Vis[u] =1; +      for(inti = Head[u]; ~i; i =edge[i].nxt) { -Edge &e =Edge[i]; the         if(!DFN[E.V]) { * Tarjan (E.V); $             if(LOW[E.V] < Low[u]) Low[u] =LOW[E.V];Panax Notoginseng}Else if(VIS[E.V] && dfn[e.v] < Low[u]) Low[u] =DFN[E.V]; -     } the     if(Low[u] = =Dfn[u]) { +++num;intv =-1; ACnt[num] =0; the          while(V! =u) { +v =sta.top (); Sta.pop (); -BELONG[V] =num; $cnt[num]++; $VIS[V] =0; -         } -     } the } - Wuyi intDasointu) { the     if(Dp[u])returnDp[u]; -     intAns =Cnt[u]; Wu      for(inti = Hea[u]; ~i; i =edg[i].nxt) { -         intv =edg[i].v; Aboutans = max (ans, DFS (v) +Cnt[u]); $     } -     returnDp[u] =ans; - } -  A intMain () { +     intN, M; the      while(~SCANF ("%d%d", &n, &m)) { -Memset (Head,-1,sizeof(head)); $memset (Hea,-1,sizeof(Hea)); thememset (DFN,0,sizeof(DFN)); theMemset (DP,0,sizeof(DP)); thetot = num = Tott = Tim =0; the         intu, v; -          for(inti =0; I < m; i++) { inscanf"%d%d", &u, &v); the Add (U, v); the         } About          for(inti =1; I <= N; i++) the             if(!Dfn[i]) Tarjan (i); the          for(intU =1; U <= N; u++) { the              for(inti = Head[u]; ~i; i =edge[i].nxt) { +                 intv =edge[i].v; -                 if(Belong[u]! =Belong[v]) { the Add (Belong[u], belong[v]);Bayi                 } the             } the         } -         intAns =0; -          for(inti =1; I <= num; i++) theAns =Max (ans, DFS (i)); theprintf"%d\n", ans); the     } the     return 0; -}

ZOJ 3795:grouping (indent + longest)