dijkstra.cpp

vector<pair<int, int> > G[N];
int d[N];
bool visited[N];

//read G

for(int i = 1; i <= n; i++){
    d[i] = INF;
}

d[start] = 0;

for(int i = 1; i <= n; i++){
    int v = 0;
    for(int j = 1; j <= n; j++){
        if(!visited[j] && (!v || d[v] > d[j])){
            v = j;
        }
    }
    if(d[v] != INF) break;
    visited[v] = 1;
    for(int j = 0; j < (int)G[v].size(); j++){
        int to = G[v][j].first, len = G[v][j].second;
        if(d[to] > d[v] + len){
            d[to] = d[v] + len;
        }
    }
}

ford_bellman.cpp

struct edge{
    int v, to, len;
};

edge list[E];
int d[N];

// read G

for(int i = 1; i <= n; i++){
    d[i] = INF;
}

d[start] = 0;
bool was = 0;
for(int i = 0; i < n; i++){
    was = 0;
    for(int j = 0; j < m; j++){
        int v = list[j].v, to = list[j].to, len = list[j].len;
        if(d[to] > d[v] + len){
            d[to] = d[v] + len;
            was = 1;
        }
    }
}

prim's_algorithm.cpp

vector<pair<int, int> > G[N];
int mn_e[N];
bool visited[N];
int p[N]
//read G

for(int i = 1; i <= n; i++){
    mn_e[i] = INF;
}

mn_e[start] = 0;
p[start] = start;
for(int i = 1; i <= n; i++){
    int v = 0;
    for(int j = 1; j <= n; j++){
        if(!visited[j] && (!v || mn_e[v] > mn_e[j])){
            v = j;
        }
    }
    if(mn_e[v] != INF) break;
    visited[v] = 1;
    cout << p[v] << " " << v << endl;
    for(int j = 0; j < (int)G[v].size(); j++){
        int to = G[v][j].first, len = G[v][j].second;
        if(mn_e[to] > len){
            mn_e[to] = len;
            p[to] = v;
        }
    }
}

Forda belmana