题目：http://codevs.cn/problem/1611/
关于题解请戳这里：http://www.cnblogs.com/hadilo/p/5892765.html
下面给一个可以A的代码，由于没有无限栈只能用手写栈Tarjan，上面题解里给的代码是递归栈的Tarjan，会RE
1 #include <cstdio> 2 #include <algorithm> 3 #include <cstring> 4 #include <vector> 5 #include <queue> 6 #include <stack> 7 #define nil 0 8 #define N 500005 9 using namespace std; 10 11 int n, m, csh[N], S, P, f[N]; 12 int u[N << 2], v[N << 2], nxt[N << 2], pnt[N], e; 13 int dfn[N], low[N], isin[N], hcash[N], tot, indx; 14 bool instack[N], vis[N]; 15 int Sta[N], stop; 16 vector <int> g[N]; 17 stack <int> s; 18 void add(int a, int b) 19 { 20 u[++e] = a; v[e] = b; 21 nxt[e] = pnt[a]; pnt[a] = e; 22 } 23 void tarjan(int x) 24 { 25 s.push(x); 26 dfn[x] = low[x] = ++indx; 27 Sta[++stop] = x; 28 instack[x] = true; 29 while(!s.empty()) 30 { 31 int t = s.top(); 32 for(int i = pnt[t]; i != nil; i = nxt[i]) 33 { 34 if(dfn[v[i]] == 0) 35 { 36 dfn[v[i]] = low[v[i]] = ++indx; 37 Sta[++stop] = v[i]; instack[v[i]] = true; 38 s.push(v[i]); 39 break; 40 } 41 } 42 if(t == s.top()) 43 { 44 for(int i = pnt[t]; i != nil; i = nxt[i]) 45 { 46 if(dfn[v[i]] > dfn[t]) low[t] = min(low[t], low[v[i]]); 47 else if(instack[v[i]]) low[t] = min(low[t], dfn[v[i]]); 48 } 49 if(dfn[t] == low[t]) 50 { 51 ++tot; 52 int j; 53 do 54 { 55 j = Sta[stop--]; 56 instack[j] = false; 57 isin[j] = tot; 58 hcash[tot] += csh[j]; 59 } while(j != t); 60 } 61 s.pop(); 62 } 63 } 64 } 65 void init() 66 { 67 int a, b; 68 scanf("%d%d", &n, &m); 69 for(int i = 1; i <= m; ++i) 70 { 71 scanf("%d%d", &a, &b); 72 add(a, b); 73 } 74 for(int i = 1; i <= n; ++i) 75 { 76 scanf("%d", &csh[i]); 77 } 78 scanf("%d%d", &S, &P); 79 for(int i = 1; i <= n; ++i) 80 { 81 if(dfn[i] == 0) 82 { 83 tarjan(i); 84 } 85 } 86 for(int i = 1; i <= n; ++i) 87 { 88 for(int j = pnt[i]; j != nil; j = nxt[j]) 89 { 90 if(isin[i] != isin[v[j]]) 91 { 92 g[isin[i]].push_back(isin[v[j]]); 93 } 94 } 95 } 96 } 97 void work() 98 { 99 queue <int> Q; 100 memset(vis, 0, sizeof(vis)); 101 memset(f, 0, sizeof(f)); 102 f[isin[S]] = hcash[isin[S]]; 103 Q.push(isin[S]); 104 vis[isin[S]] = true; 105 while(!Q.empty()) 106 { 107 int t = Q.front(); 108 Q.pop(); 109 vis[t] = false; 110 for(int i = 0; i < g[t].size(); ++i) 111 { 112 if(f[g[t][i]] < f[t] + hcash[g[t][i]]) 113 { 114 f[g[t][i]] = f[t] + hcash[g[t][i]]; 115 if(!vis[g[t][i]]) 116 { 117 vis[g[t][i]] = true; 118 Q.push(g[t][i]); 119 } 120 } 121 } 122 } 123 int ans = 0, a; 124 for(int i = 1; i <= P; ++i) 125 { 126 scanf("%d", &a); 127 ans = max(ans, f[isin[a]]); 128 } 129 printf("%d ", ans); 130 } 131 int main() 132 { 133 init(); 134 work(); 135 return 0; 136 }
版权所有，转载请联系作者，违者必究
QQ：740929894