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| #include <algorithm> #include <cassert> #include <cmath> #include <cstdio> #include <cstring> #include <fstream> #include <iostream> #include <queue> #include <vector> using namespace std;
typedef long long int64;
const int INF = 0x3f3f3f3f; const int MAXN = 1510;
#include <cctype> #include <cstdio>
template <typename T = int> inline T read() { T X = 0, w = 0; char ch = 0; while (!isdigit(ch)) { w |= ch == '-'; ch = getchar(); } while (isdigit(ch)) { X = (X << 3) + (X << 1) + (ch ^ 48); ch = getchar(); } return w ? -X : X; }
class lfs { public: lfs(int N) { memset(head, -1, sizeof head); ecnt = 0; n = N; } void adde(int from, int to, int w) { Edge now; now.to = to; now.w = w; now.next = head[from]; now.mark1 = now.mark2 = false; e.push_back(now); head[from] = ecnt++; } void addde(int a, int b, int w) { adde(a, b, w); adde(b, a, w); }
protected: struct Edge { int to, next, w; bool mark1, mark2; }; vector<Edge> e; int head[MAXN]; int ecnt; int n; };
class long_path : public lfs { public: long_path(int n) : lfs(n) {} int solve() { memset(dp, -1, sizeof dp); int ans = 0; for (int i = 1; i <= n; i++) { if (dp[i] == -1) { dfs(i, -1); } } for (int i = 1; i <= n; i++) { ans = max(ans, dp[i]); } return ans; }
protected: int dp[MAXN];
void dfs(int u, int fa) { dp[u] = 0; for (int i = head[u]; i != -1; i = e[i].next) { int v = e[i].to; if (v == fa) continue; if (dp[v] == -1) { dfs(v, u); } dp[u] = max(dp[u], dp[v] + e[i].w); } } };
class spfa : public lfs { public: spfa(int n) : lfs(n) { memset(dis, INF, sizeof dis); } int dis[MAXN]; void solve(int s) { memset(ins, false, sizeof ins); memset(dis, INF, sizeof dis); queue<int> q; q.push(s); ins[s] = true; dis[s] = 0; while (!q.empty()) { int now = q.front(); q.pop(); ins[now] = false; for (int i = head[now]; i != -1; i = e[i].next) { int w = e[i].w; int v = e[i].to; if (dis[now] + w < dis[v]) { dis[v] = dis[now] + w; if (!ins[v]) { q.push(v); ins[v] = true; } } } } }
void mark1(int s, int t) { solve(s); int* dis1 = new int[MAXN]; memcpy(dis1, dis, sizeof dis); solve(t); for (int u = 1; u <= n; u++) { for (int i = head[u]; i != -1; i = e[i].next) { int v = e[i].to; if (dis1[u] + e[i].w + dis[v] == dis1[t]) { e[i].mark1 = true; } } } delete[] dis1; }
void mark2(int s, int t) { solve(s); int* dis1 = new int[MAXN]; memcpy(dis1, dis, sizeof dis); solve(t); for (int u = 1; u <= n; u++) { for (int i = head[u]; i != -1; i = e[i].next) { int v = e[i].to; if (dis1[u] + e[i].w + dis[v] == dis1[t]) { e[i].mark2 = true; } } } delete[] dis1; }
void create_dag(lfs* dag1, lfs* dag2) { for (int u = 1; u <= n; u++) { for (int i = head[u]; i != -1; i = e[i].next) { int v = e[i].to; if (e[i].mark1 && e[i].mark2) { dag1->adde(u, v, e[i].w); } if (e[i].mark1 && e[i^1].mark2) { dag2->adde(u, v, e[i].w); } } } }
private: bool ins[MAXN]; };
int main() { int n = read(); int m = read(); int s1 = read(); int t1 = read(); int s2 = read(); int t2 = read();
spfa* all = new spfa(n); for (int i = 1; i <= m; i++) { int u = read(); int v = read(); int w = read(); all->addde(u, v, w); } all->mark1(s1, t1); all->mark2(s2, t2); long_path* dag1 = new long_path(n); long_path* dag2 = new long_path(n); all->create_dag(dag1, dag2); cout << max(dag1->solve(), dag2->solve()) << endl; return 0; }
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