关键路劲算法c++实现

以下是关键路径算法的C++实现，其中包括了关键路径算法的主要步骤和数据结构：

#include <iostream>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;

const int MAXN = 1005;
const int INF = 0x3f3f3f3f;

struct Edge {
    int to, w;
    Edge(int to, int w) : to(to), w(w) {}
};

vector<Edge> G[MAXN];
int inDegree[MAXN], earliest[MAXN], latest[MAXN];
bool vis[MAXN];

void init(int n) {
    memset(inDegree, 0, sizeof(inDegree));
    memset(earliest, 0, sizeof(earliest));
    memset(latest, INF, sizeof(latest));
    memset(vis, false, sizeof(vis));
    for (int i = 0; i <= n; i++) {
        G[i].clear();
    }
}

void addEdge(int u, int v, int w) {
    G[u].push_back(Edge(v, w));
    inDegree[v]++;
}

bool topologicalSort(int n) {
    queue<int> q;
    for (int i = 1; i <= n; i++) {
        if (inDegree[i] == 0) {
            q.push(i);
            vis[i] = true;
        }
    }
    while (!q.empty()) {
        int u = q.front();
        q.pop();
        for (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i].to;
            int w = G[u][i].w;
            inDegree[v]--;
            if (inDegree[v] == 0) {
                q.push(v);
                vis[v] = true;
            }
            earliest[v] = max(earliest[v], earliest[u] + w);
        }
    }
    for (int i = 1; i <= n; i++) {
        if (!vis[i]) {
            return false;
        }
    }
    return true;
}

void calcLatest(int n) {
    queue<int> q;
    for (int i = 1; i <= n; i++) {
        if (inDegree[i] == 0) {
            q.push(i);
        }
    }
    while (!q.empty()) {
        int u = q.front();
        q.pop();
        for (int i = 0; i < G[u].size(); i++) {
            int v = G[u][i].to;
            int w = G[u][i].w;
            inDegree[v]--;
            if (inDegree[v] == 0) {
                q.push(v);
            }
            latest[u] = min(latest[u], latest[v] - w);
        }
    }
}

int main() {
    int n, m;
    cin >> n >> m;
    init(n);
    for (int i = 0; i < m; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        addEdge(u, v, w);
    }
    if (!topologicalSort(n)) {
        cout << "No solution" << endl;
        return 0;
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        ans = max(ans, earliest[i]);
    }
    cout << ans << endl;
    calcLatest(n);
    for (int i = 1; i <= n; i++) {
        for (int j = 0; j < G[i].size(); j++) {
            int v = G[i][j].to;
            int w = G[i][j].w;
            int e = earliest[i], l = latest[v] - w;
            if (e == l) {
                cout << i << "->" << v << endl;
            }
        }
    }
    return 0;
}