POJ3160 strong connectivity + Memory search

Test instructions: There is an n-point m-side of the direction of the graph, each point has its own weight, can be negative, now from a point to go, until you can not go to other points, each through a point, you may choose to get or not to get its weight, each point can go multiple times, but the right value can only be obtained once, Ask how many weights you can get at the end.

Each point can go more than once, the weight can only be obtained once, passing the time of the weight may not be obtained, so we just need to consider the right value on the line. We can get the weights of the points in a strong connected component, so we get the first one with a forward loop, and then we start with DFS at the point where each entry is 0, and the cumulative maximum weight will be the line.

1#include <stdio.h>2#include <string.h>3#include <stack>4#include <queue>5 using namespacestd;6 7 Const intmaxn=3e4+5;8 Const intmaxm=2e5+5;9 Ten inthead[2][maxn],point[2][maxm],nxt[2][maxm],size[2]; One intn,t,scccnt; A intSTX[MAXN],LOW[MAXN],SCC[MAXN],NUM[MAXN],ID[MAXN],V[MAXN]; - intDP[MAXN]; -stack<int>S; the  - intMaxintAintb) {returnA>b?a:b;} -  - voidinit () { +memset (head,-1,sizeof(head)); -size[0]=size[1]=0; +memset (NUM,0,sizeof(num)); Amemset (ID,0,sizeof(ID)); atmemset (dp,-1,sizeof(DP)); - } -  - voidAddintAintBintC=0){ -point[c][size[c]]=b; -nxt[c][size[c]]=Head[c][a]; inhead[c][a]=size[c]++; - } to  + voidDfsints) { -stx[s]=low[s]=++T; the S.push (S); *      for(inti=head[0][s];~i;i=nxt[0][i]) { $         intj=point[0][i];Panax Notoginseng         if(!Stx[j]) { - Dfs (j); thelow[s]=min (low[s],low[j]); +         } A         Else if(!Scc[j]) { thelow[s]=min (low[s],stx[j]); +         } -     } $     if(low[s]==Stx[s]) { $scccnt++; -          while(1){ -             intu=S.top (); S.pop (); thescc[u]=scccnt; -Num[scccnt]+=v[u]>0? V[u]:0;Wuyi             if(S==u) Break; the         } -     } Wu } -  About voidSETSCC () { $memset (STX,0,sizeof(STX)); -memset (SCC,0,sizeof(SCC)); -T=scccnt=0; -      for(intI=1; i<=n;++i)if(!Stx[i]) DFS (i); A      for(intI=1; i<=n;++i) { +          for(intj=head[0][i];~j;j=nxt[0][j]) { the             intk=point[0][j]; -             if(scc[i]!=Scc[k]) { $Add (Scc[i],scc[k],1); theid[scc[k]]++; the             } the         } the     } - } in  the intDFS1 (ints) { the     if(~dp[s])returnDp[s]; About     intmaxx=0; the      for(inti=head[1][s];~i;i=nxt[1][i]) { the         intj=point[1][i]; themaxx=Max (MAXX,DFS1 (j)); +     } -dp[s]=maxx+Num[s]; the     returnDp[s];Bayi } the  the intMain () { -     intm; -      while(SCANF ("%d%d", &n,&m)! =EOF) { the init (); the          for(intI=1; i<=n;++i) scanf ("%d",&v[i]); the          while(m--){ the             intb; -scanf"%d%d",&a,&b); thea++; theb++; the Add (A, b);94         } the SETSCC (); the         intans=0; the          for(intI=1; i<=scccnt;++i) {98             if(!id[i]) ans=Max (ANS,DFS1 (i)); About         } -printf"%d\n", ans);101     }102     return 0;103}

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POJ3160 strong connectivity + Memory search