负载平衡问题

我的方法比较复杂
S向每个仓库连初始量的边，每个仓库拆成两个，后往前连INF边，前往T连平均值的边，边权都是0
再S每个仓库向相邻仓库的第二个点连INF边，边权为1
再费用流即为答案

# include <bits/stdc++.h>
# define RG register
# define IL inline
# define Fill(a, b) memset(a, b, sizeof(a))
# define Copy(a, b) memcpy(a, b, sizeof(a))
using namespace std;
typedef long long ll;
const int _(510), __(1e6 + 10), INF(2e9);

IL ll Read(){
    char c = '%'; ll x = 0, z = 1;
    for(; c > '9' || c < '0'; c = getchar()) if(c == '-') z = -1;
    for(; c >= '0' && c <= '9'; c = getchar()) x = x * 10 + c - '0';
    return x * z;
}

int n, cnt, fst[_], w[__], to[__], nxt[__], dis[_], vis[_], S, T, cost[__], pe[_], pv[_], max_flow, min_cost, sum;
queue <int> Q;

IL void Add(RG int u, RG int v, RG int f, RG int co){
    cost[cnt] = co; w[cnt] = f; to[cnt] = v; nxt[cnt] = fst[u]; fst[u] = cnt++;
    cost[cnt] = -co; w[cnt] = 0; to[cnt] = u; nxt[cnt] = fst[v]; fst[v] = cnt++;
}

IL bool Bfs(){
    Q.push(S); Fill(dis, 127); dis[S] = 0; vis[S] = 1;
    while(!Q.empty()){
        RG int u = Q.front(); Q.pop();
        for(RG int e = fst[u]; e != -1; e = nxt[e]){
            if(!w[e] || dis[to[e]] <= dis[u] + cost[e]) continue;
            dis[to[e]] = dis[u] + cost[e];
            pe[to[e]] = e; pv[to[e]] = u;
            if(!vis[to[e]]) vis[to[e]] = 1, Q.push(to[e]);
        }
        vis[u] = 0;
    }
    if(dis[T] >= dis[T + 1]) return 0;
    RG int ret = INF;
    for(RG int u = T; u != S; u = pv[u]) ret = min(ret, w[pe[u]]);
    for(RG int u = T; u != S; u = pv[u]) w[pe[u]] -= ret, w[pe[u] ^ 1] += ret;
    min_cost += ret * dis[T]; max_flow += ret;
    return 1;
}

int main(RG int argc, RG char *argv[]){
    Fill(fst, -1); n = Read(); T = 2 * n + 1;
    for(RG int i = 1, v; i <= n; ++i){
        v = Read(); sum += v;
        Add(S, i, v, 0); Add(i + n, i, INF, 0);
        if(i == 1) Add(i, n + n, INF, 1);
        if(i == n) Add(i, 1 + n, INF, 1);
        if(i != 1) Add(i, i + n - 1, INF, 1);
        if(i != n) Add(i, i + n + 1, INF, 1);
    }
    sum /= n;
    for(RG int i = 1; i <= n; ++i) Add(i, T, sum, 0);
    while(Bfs());
    printf("%d
", min_cost);
    return 0;
}