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ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#397690 | #2208. Flow | alpha1022 | WA | 6ms | 4048kb | C++14 | 3.0kb | 2024-04-24 15:58:36 | 2024-04-24 15:58:36 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
template<class Z, class ZC>
struct CostFlow {
int n;
vector<vector<tuple<int, int, Z, ZC>>> g;
CostFlow(int n) : n(n), g(n) {}
void addEdge(int u, int v, Z c, ZC w) {
int ru = g[u].size(), rv = g[v].size();
g[u].emplace_back(v, rv, c, w), g[v].emplace_back(u, ru, 0, -w);
}
pair<Z, ZC> dinic(int s, int t) {
vector<ZC> h(n), dis(n);
vector<int> level(n), inQueue(n), cur(n);
auto getH = [&]() {
fill_n(h.begin(), n, numeric_limits<ZC>::max());
queue<int> q; q.push(s), h[s] = 0, inQueue[s] = 1;
while (!q.empty()) {
int u = q.front(); q.pop(), inQueue[u] = 0;
for (auto [v, _, c, w]: g[u]) {
if (c && h[v] > h[u] + w) {
h[v] = h[u] + w;
if (!inQueue[v]) q.push(v), inQueue[v] = 1;
}
}
}
};
getH();
if (h[t] == numeric_limits<ZC>::max()) return {0, 0};
auto getLevel = [&]() {
fill_n(dis.begin(), n, numeric_limits<ZC>::max());
priority_queue<pair<ZC, int>, vector<pair<ZC, int>>, greater<pair<ZC, int>>> pQ;
pQ.emplace(dis[s] = 0, s);
while (!pQ.empty()) {
auto [d, u] = pQ.top(); pQ.pop();
if (d > dis[u]) continue;
for (auto [v, _, c, w]: g[u]) {
w += h[u] - h[v];
if (c && dis[v] > dis[u] + w) pQ.emplace(dis[v] = dis[u] + w, v);
}
}
queue<int> q; fill_n(level.begin(), n, -1), q.push(s), level[s] = 0;
while (!q.empty()) {
int u = q.front(); q.pop();
for (auto [v, _, c, w]: g[u])
if (c && dis[v] == dis[u] + w + h[u] - h[v] && level[v] == -1) level[v] = level[u] + 1, q.push(v);
}
};
Z ret = 0; ZC cost = 0;
function<Z(int, Z)> cap = [&](int u, Z lim) {
if (u == t) return lim;
Z ret = 0;
for (; cur[u] && ret < lim; --cur[u]) {
auto &[v, rev, c, w] = g[u][cur[u] - 1];
if (c && dis[v] == dis[u] + w + h[u] - h[v] && level[v] == level[u] + 1) {
Z flow = cap(v, min(lim - ret, c));
ret += flow, cost += flow * w, c -= flow, get<2>(g[v][rev]) += flow;
if (ret == lim) return ret;
}
}
return ret;
};
while (getLevel(), level[t] != -1) {
for (int i = 0; i < n; ++i) cur[i] = g[i].size();
ret += cap(s, numeric_limits<Z>::max());
for (int i = 0; i < n; ++i) h[i] += dis[i];
}
return {ret, cost};
}
};
int main() {
int n, m; scanf("%d%d", &n, &m);
int ans = 0;
vector<int> sum(n);
CostFlow<int, int> costFlow(n + 2);
int s = n, t = n + 1;
for (int i = 0; i < m; ++i) {
int u, v, c; scanf("%d%d%d", &u, &v, &c), --u, --v;
sum[u] -= c, sum[v] += c, ans += c, costFlow.addEdge(v, u, c, 1);
}
for (int i = 0; i < n; ++i)
if (sum[i] < 0) costFlow.addEdge(s, i, -sum[i], 0);
else if (sum[i] > 0) costFlow.addEdge(i, t, sum[i], 0);
printf("%d\n", ans -= costFlow.dinic(s, t).second);
}
详细
Test #1:
score: 0
Wrong Answer
time: 6ms
memory: 4048kb