版权声明:反正也没有人会转,下一个 https://blog.csdn.net/drtlstf/article/details/82155463
Description
Input
第1行输入N,之后N行每行描述一条水管,前两个英文字母表示水管的两端(大小写字母是不一样的),后一个整数表示水管的流量,流量不会超过1000.
Output
一个整数,表示总流量.
Sample Input
5
A B 3
B C 3
C D 5
D Z 4
B Z 6
Sample Output
3
真·模板题
代码:
#include <iostream> // 模板就不用说了
#include <cstring>
#include <queue>
#define SIZE 501
#define INF 2e+09
using namespace std;
struct edge
{
int to, cap, reverse;
};
vector<edge> graph[SIZE];
int depth[SIZE];
bool bfs(void)
{
int u, i, v;
queue<int> q;
memset(depth, -1, sizeof (depth));
depth['A'] = 0;
q.push('A');
while (!q.empty())
{
u = q.front();
if (u == 'Z')
{
return true;
}
q.pop();
for (i = 0; i < graph[u].size(); ++i)
{
v = graph[u][i].to;
if ((graph[u][i].cap) && (depth[v] == -1))
{
depth[v] = depth[u] + 1;
q.push(v);
}
}
}
return false;
}
int dfs(int u, int flow)
{
int i, v, ret = 0, delta;
if ((!flow) || (u == 'Z'))
{
return flow;
}
for (i = 0; i < graph[u].size(); ++i)
{
edge &temp = graph[u][i];
v = temp.to;
if ((depth[v] == depth[u] + 1) && (temp.cap > 0))
{
delta = dfs(v, min(flow - ret, temp.cap));
if (delta > 0)
{
ret += delta;
temp.cap -= delta;
graph[v][temp.reverse].cap += delta;
if (ret == flow)
{
return ret;
}
}
}
}
return ret;
}
int dinic(void) // 日常Dinic
{
int ret = 0, delta;
while (bfs())
{
delta = dfs('A', INF);
if (!delta)
{
return ret;
}
ret += delta;
}
return ret;
}
int main(int argc, char** argv)
{
int m, cap;
char u, v;
scanf("%d", &m);
while (m--)
{
cin >> u >> v; // 不知道为什么scanf字符会出问题,只得用cin输入
scanf("%d", &cap);
graph[u].push_back({v, cap, graph[v].size()});
graph[v].push_back({u, 0, graph[u].size() + 1});
}
printf("%d", dinic());
return 0;
}