There is a time limit on the order in which time occurs. Time A cannot occur until its precursor activities have completed.
Edge: Represents the duration of the activity, and the corresponding activity time must be performed between the two events.
Point: Represents an event
Four key attributes
Ve[i]: Indicates the earliest time that event I occurred;
Vl[i]: Indicates the latest occurrence of event I
e[i]: indicates the earliest occurrence of activity i;
l[i]: Indicates the latest occurrence of activity i;
Calculation process:
Make l[i] = e[i] indicate that an activity can be performed immediately as long as it is possible;
#include <iostream> #include <cstring> #include <queue> using namespace std; const int maxn = 1e4 + 10; const int maxm = 1e6 + 10; const int INF = 0x3f3f3f3f; int head1[maxn], pnt1[maxm], nxt1[maxm], cost1[maxm], ecnt1; int head2[maxn], pnt2[maxm], nxt2[maxm], cost2[maxm], ecnt2; inline void addedge(int u, int v, int c) { pnt1[ecnt1] = v, cost1[ecnt1] = c, nxt1[ecnt1] = head1[u], head1[u] = ecnt1++; pnt2[ecnt2] = u, cost2[ecnt2] = c, nxt2[ecnt2] = head2[v], head2[v] = ecnt2++; } int dis1[maxn];//dis1[i] denotes the earliest time that event I can occur int dis2[maxn];//dis2[i] indicates the latest time that event I can occur bool mark[maxn]; void HeadToTail(int st, int ed) { queue<int> que; memset(mark, false, sizeof mark); memset(dis1, -1, sizeof dis1); que.push(st); dis1[st] = 0; while(!que.empty()) { int u = que.front(); que.pop(); mark[u] = false; for (int i = head1[u];~i;i = nxt1[i]) { int v = pnt1[i], c = cost1[i]; //Finding the Longest Path if (dis1[u] + cost1[i] > dis1[v]) { dis1[v] = dis1[u] + cost1[i]; if (!mark[v]) { mark[v] = true; que.push(v); } } } } } void TailToHead(int st, int ed) { queue<int> que; memset(mark, false, sizeof mark); memset(dis2, INF, sizeof dis2); dis2[ed] = dis1[ed];//The earliest time inherited mark[ed] = true; que.push(ed); while(!que.empty()) { int u = que.front(); que.pop(); mark[u] = false; for (int i = head2[u];~i;i = nxt2[i]) { int v = pnt2[i], c = cost2[i]; if (dis2[v] > dis2[u] - c) {//Shortest path, no loops dis2[v] = dis2[u] - c; if (!mark[v]) { mark[v] = true; que.push(v); } } } } } inline void AOENetWork(int st, int ed) { HeadToTail(st, ed); TailToHead(ed, ed); } int main() { return 0; }