Everybody makes mistakes :P

Write down all the inequalities for each day, like: type1 + type2 + ... >= Ai. Add a free variable to each of them: type1 + type2 + ... - Bi = Ai. Now subtract all consecutive equations, each variable will occur exactly twice. Add an edge to network for each of them. Add an edge from the source to each positive equation, and an edge from each negative equation to the target.

Here's my code:

void MAIN(){
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= n; i ++) scanf("%d", a+i);
    int s = N - 1, t = N - 2;
    for(int i = 1; i <= n + 1; i ++){
        if(a[i]-a[i-1] < 0) mfmc.add_edge(s, i, a[i-1]-a[i], 0);
        else mfmc.add_edge(i, t, a[i] - a[i-1], 0);
    }
    for(int i = 1; i <= n; i ++){
        mfmc.add_edge(i, i+1, 1<<30, 0);
    }
    while(m --){
        int l, r, c;
        scanf("%d%d%d", &l, &r, &c);
        mfmc.add_edge(r+1, l, 1<<30, c);
    }
    cout << mfmc.mincost(s, t) << endl;
}