L2-001 紧急救援

合集 - 模拟(54)

1.G. Vlad and Trouble at MIT2024-02-202.P2899 [USACO08JAN] Cell Phone Network G2024-02-203.Watering an Array2024-02-234.P2055 [ZJOI2009] 假期的宿舍2024-03-085.T432579 大西洋船王2024-03-086.T432580 星云 hard ver.2024-03-087.P7072 [CSP-J2020] 直播获奖2024-03-098.E - Insert or Erase2024-03-109.D - String Bags2024-03-1010.P2671 [NOIP2015 普及组] 求和2024-03-1011.P1884 [USACO12FEB] Overplanting S2024-03-1012.F. Microcycle2024-03-1213.E. Increasing Subsequences__22024-03-1314.G. Path Prefixes2024-03-1415.F. Rudolf and Imbalance2024-03-1416.P1355 神秘大三角2024-03-2017.[ARC172A] Chocolate2024-03-2518.F. 0, 1, 2, Tree!2024-03-2919.E. Nearly Shortest Repeating Substring2024-03-2920.P1354 房间最短路问题2024-03-2921.P3258 [JLOI2014] 松鼠的新家2024-04-0222.P3052 [USACO12MAR] Cows in a Skyscraper G2024-04-0523.P1337 [JSOI2004] 平衡点 / 吊打XXX2024-04-0724.P3745 [六省联考 2017] 期末考试2024-04-0825.D. Inaccurate Subsequence Search2024-04-0926.E. Long Inversions2024-04-0927.C. Deep Down Below2024-04-0928.C. Rings2024-04-0929.F. Unfair Game2024-04-1030.C. Inversion Graph2024-04-1031.D. Cross Coloring2024-04-1232.D2. Set To Max (Hard Version)2024-04-1233.C. Array Game2024-04-1234.F. Alex's whims2024-04-1235.Queue Sort2024-04-1236.P10252 线性变换2024-04-1637.P10288 [GESP样题 八级] 区间2024-04-1638.P2161 [SHOI2009] 会场预约2024-04-17

39.L2-001 紧急救援2024-04-18

40.L2-002 链表去重2024-04-1841.L2-013 红色警报2024-04-1842.L2-014 列车调度2024-04-1943.L2-022 重排链表2024-04-1944.L2-023 图着色问题2024-04-1945.L2-039 清点代码库2024-04-1946.L2-034 口罩发放2024-04-1947.L3-037 夺宝大赛2024-04-2348.仓库规划2024-04-2349.因子化简2024-04-2350.C. Torn Lucky Ticket2024-04-2751.俄罗斯方块2024-05-1452.F. Cutting Game2024-05-2153.D. Prefix Permutation Sums2024-06-1754.P3304 [SDOI2013] 直径2024-07-15

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原题链接

题解

确定起点和终点，求救援人数最长，路径最短的路径，只需要集群算法中优先队列中重载比较符修改一下就就行，由于数据量很小，所以输出路径的时候搜索就行（最优解唯一）

code

#include<bits/stdc++.h>
using namespace std;

struct node
{
    int to,val;
};
vector<node> G[505];

int people[505]={0};
int help[505]={0};
int dis[505];
int path[505]={0};
int vis[505]={0};
stack<int> st;
int flag=0;
int n,m,s,d;

struct fresh
{
    int to,pre,val;
    bool operator<(const fresh &b)const
    {
        if(val!=b.val)return val>b.val;//dis
        else return help[pre]+people[to]<help[b.pre]+people[b.to];//help
    }
};
void ss(int walk,int cure,int now)
{
    if(walk==0&&cure==0)
    {
        if(now!=d) return;
        flag=1;
        st.push(now);
        return ;
    }
    if(walk<=0||cure<=0||now==d) return;

    for(auto next:G[now])
    {
        int to=next.to,val=next.val;
        if(!vis[to])
        {
            vis[to]=1;
            ss(walk-val,cure-people[to],to);
            vis[to]=0;
        }

        if(flag)
        {
            st.push(now);
            return ;
        }
    }
}

int main()
{
    memset(dis,0x3f,sizeof dis);

    cin>>n>>m>>s>>d;

    for(int i=0;i<n;i++) cin>>people[i];

    for(int i=1;i<=m;i++)
    {
        int x,y,c;
        cin>>x>>y>>c;
        G[x].push_back({y,c});
        G[y].push_back({x,c});
    }

    priority_queue<fresh> q;
    q.push({s,s,0});
    path[s]=1;
    while(q.size())
    {
        int now=q.top().to,pre=q.top().pre,val=q.top().val;
        q.pop();
        if(dis[now]<val) continue;
        else if(dis[now]==val)
        {
            path[now]+=path[pre];
            continue;
        }
        dis[now]=val;
        path[now]=path[pre];
        help[now]=help[pre]+people[now];
        for(auto next:G[now]) q.push({next.to,now,next.val+dis[now]});
    }
    cout<<path[d]<<" "<<help[d]<<endl;

    ss(dis[d],help[d]-people[s],s);
    while(st.size())
    {
        cout<<st.top();
        st.pop();
        if(st.size()) cout<<" ";
    }
    return 0;
}