【luogu P1113 杂务】 题解
题目链接:https://www.luogu.org/problemnew/show/P1113
菜
#include <queue>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 50000 + 10;
const int inf = 0x7fffffff;
int n, m, s, dis[maxn], w[maxn], du[maxn], ans;
bool vis[maxn];
queue<int> q;
struct edge{
int from, to, next, len;
}e[maxn<<2];
int head[maxn], cnt;
void add(int u, int v, int w)
{
e[++cnt].from = u;
e[cnt].len = w;
e[cnt].next = head[u];
e[cnt].to = v;
head[u] = cnt;
}
void SPFA(int s)
{
while(!q.empty()) q.pop();
for(int i = 1; i <= n; i++) dis[i] = inf, vis[i] = 0;
q.push(s);
dis[s] = w[s];
vis[s] = 1;
while(!q.empty())
{
int now = q.front(); q.pop();
vis[now] = 0;
for(int i = head[now]; i != -1; i = e[i].next)
{
if(dis[e[i].to] > dis[now] + e[i].len)
{
dis[e[i].to] = dis[now] + e[i].len;
if(!vis[e[i].to])
{
q.push(e[i].to);
vis[e[i].to] = 1;
}
}
}
}
}
int main()
{
memset(head, -1, sizeof(head));
scanf("%d",&n);
for(int i = 1; i <= n; i++)
{
int uu, vv, ww;
scanf("%d%d",&vv,&ww);
w[vv] = -1*ww;
while(scanf("%d",&uu) && uu != 0)
{
add(uu, vv, -1*ww);
du[vv]++;
}
}
//for(int i = 1; i <= n; i++) cout<<w[i]<<" ";
for(int i = 1; i <= n; i++)
{
ans = inf;
if(du[i] == 0) SPFA(i);
for(int j = 1; j <= n; j++)
{
if(ans > dis[j])
ans = dis[j];
}
}
printf("%d",-ans);
return 0;
}
隐约雷鸣,阴霾天空,但盼风雨来,能留你在此。
隐约雷鸣,阴霾天空,即使天无雨,我亦留此地。
![](https://images.cnblogs.com/cnblogs_com/MisakaAzusa/1169114/o_a0c3752e09f79052b15f108c0cf3d7ca7acbd5b0.gif)