mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-12-12 02:46:27 +00:00
132 lines
2.6 KiB
C++
132 lines
2.6 KiB
C++
|
#include <cstring>
|
||
|
#include <iostream>
|
||
|
#include <queue>
|
||
|
|
||
|
using std::cin;
|
||
|
using std::cout;
|
||
|
const char endl = '\n';
|
||
|
|
||
|
const int N = 105,
|
||
|
M = 2005,
|
||
|
INF = 0x3f3f3f3f;
|
||
|
|
||
|
int n, s, t, a[N], sum, avg, cost;
|
||
|
|
||
|
// Graph
|
||
|
int idx, head[N], ver[M << 1], next[M << 1];
|
||
|
std::pair<int, int> edge[M << 1];
|
||
|
// <flow, cost>
|
||
|
|
||
|
void add(int u, int v, int flow, int cost) {
|
||
|
next[idx] = head[u];
|
||
|
ver[idx] = v;
|
||
|
edge[idx] = std::make_pair(flow, cost);
|
||
|
head[u] = idx++;
|
||
|
}
|
||
|
|
||
|
// Dinic
|
||
|
int dist[N];
|
||
|
bool vis[N];
|
||
|
|
||
|
bool spfa() {
|
||
|
std::memset(vis, 0x00, sizeof(vis));
|
||
|
std::memset(dist, 0x3f, sizeof(dist));
|
||
|
|
||
|
std::queue<int> q;
|
||
|
q.push(s);
|
||
|
dist[s] = 0;
|
||
|
vis[s] = true;
|
||
|
|
||
|
while (!q.empty()) {
|
||
|
int u = q.front();
|
||
|
q.pop();
|
||
|
vis[u] = false;
|
||
|
|
||
|
for (int i = head[u]; ~i; i = next[i]) {
|
||
|
int v = ver[i],
|
||
|
c = edge[i].first,
|
||
|
w = edge[i].second;
|
||
|
|
||
|
if (dist[v] > dist[u] + w && c > 0) {
|
||
|
dist[v] = dist[u] + w;
|
||
|
if (!vis[v]) {
|
||
|
q.push(v);
|
||
|
vis[v] = true;
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
return dist[t] != INF;
|
||
|
}
|
||
|
|
||
|
int dinic(int u, int limit) {
|
||
|
if (u == t) return limit;
|
||
|
|
||
|
int flow = 0;
|
||
|
vis[u] = true;
|
||
|
for (int i = head[u]; ~i && flow < limit; i = next[i]) {
|
||
|
int v = ver[i],
|
||
|
c = edge[i].first,
|
||
|
w = edge[i].second;
|
||
|
|
||
|
if (dist[v] == dist[u] + w && c && !vis[v]) {
|
||
|
int k = dinic(v, std::min(c, limit - flow));
|
||
|
if (!k) dist[v] = INF;
|
||
|
edge[i].first -= k;
|
||
|
edge[i ^ 1].first += k;
|
||
|
flow += k;
|
||
|
cost += k * w;
|
||
|
}
|
||
|
}
|
||
|
vis[u] = false;
|
||
|
|
||
|
return flow;
|
||
|
}
|
||
|
|
||
|
int main() {
|
||
|
std::ios::sync_with_stdio(false);
|
||
|
|
||
|
memset(head, 0xff, sizeof(head));
|
||
|
|
||
|
cin >> n;
|
||
|
for (int i = 1; i <= n; i++) {
|
||
|
cin >> a[i];
|
||
|
sum += a[i];
|
||
|
}
|
||
|
avg = sum / n;
|
||
|
|
||
|
s = 0, t = n + 1;
|
||
|
for (int i = 1; i <= n; i++) {
|
||
|
if (a[i] - avg > 0) {
|
||
|
add(s, i, a[i] - avg, 0);
|
||
|
add(i, s, 0, 0);
|
||
|
} else if (a[i] - avg < 0) {
|
||
|
add(i, t, avg - a[i], 0);
|
||
|
add(t, i, 0, 0);
|
||
|
}
|
||
|
}
|
||
|
|
||
|
for (int i = 1; i <= n; i++) {
|
||
|
if (i > 1) {
|
||
|
add(i, i - 1, INF, 1);
|
||
|
add(i - 1, i, 0, -1);
|
||
|
}
|
||
|
if (i < n) {
|
||
|
add(i, i + 1, INF, 1);
|
||
|
add(i + 1, i, 0, -1);
|
||
|
}
|
||
|
}
|
||
|
|
||
|
add(1, n, INF, 1);
|
||
|
add(n, 1, 0, -1);
|
||
|
add(n, 1, INF, 1);
|
||
|
add(1, n, 0, -1);
|
||
|
|
||
|
while (spfa()) dinic(s, INF);
|
||
|
|
||
|
cout << cost << endl;
|
||
|
|
||
|
return 0;
|
||
|
}
|