SDUWH 数据结构 最短路径

如题，求单源单汇最短路径

把模板题洛谷P3371或P4779一套就好了

SPFA和Dijkstra朴素/堆优化见https://blog.csdn.net/qq_35850147/article/details/88533218

#include <iostream>
#include <cstring>
#include <queue>
#include <algorithm>
using namespace std;

const int maxn = 1e5 + 10;
const int maxm = 2e5 + 10;
bool vis[maxn];
int cnt, top, head[maxn], dis[maxn], pre[maxn], sta[maxn]; // cnt为边计数，top为答案路径栈顶，head[i]为该顶点的边集首下标，dis[i]缓存松弛过程中s到i的距离，pre[]保存答案路径前驱，sta[]保存答案路径
string place[maxn]; // 保存地点名称
struct edge { int v, w, next; } e[maxm]; // 链式前向星存图
struct node
{
    int u, w;
    bool operator < (const node &n) const { return w > n.w; }
};
priority_queue<node> q; // Dijkstra堆优化
 
inline const int read()
{
    int x = 0, f = 1;
    char ch = getchar();
    while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); }
    while (ch >= '0' && ch <= '9') { x = (x << 3) + (x << 1) + ch - '0'; ch = getchar(); }
    return x * f;
}
 
void addEdge(int u, int v, int w)
{
    e[cnt].v = v;
    e[cnt].w = w;
    e[cnt].next = head[u];
    head[u] = cnt++;
}
 
void dijkstra(int src)
{
    memset(dis, 0x3f, sizeof(dis));
    dis[src] = 0;
    q.push(node{src, 0});
    while (!q.empty())
    {
        int u = q.top().u; q.pop();
        if (vis[u]) continue;
        vis[u] = true;
        for (int i = head[u]; ~i; i = e[i].next)
        {
            int v = e[i].v, w = e[i].w;
            if (dis[v] > dis[u] + w)
            {
                dis[v] = dis[u] + w;
                pre[v] = u;
                q.push(node{v, dis[v]});
            }
        }
    }
}

int main()
{
    printf("请分别输入地点总数、直达路径总数：");
    int n = read(), m = read();
    for (int i = 1; i <= n; i++)
    {
        printf("请输入第%d个地点的名称：", i);
        scanf("%s", &place[i][0]);
    }
    memset(head, -1, sizeof(head));
    for (int i = 1; i <= m; i++)
    {
        printf("请分别输入第%d条直达路径的两端点编号和长度：", i);
        int u = read(), v = read(), w = read();
        addEdge(u, v, w);
        addEdge(v, u, w);
    }
    printf("请输入源点编号和终点编号：");
    int s = read(), t = read();
    dijkstra(s);
    for (int i = t; i != s; i = pre[i]) sta[top++] = i;
    for (int i = top - 1, last = s; i >= 0; i--)
    {
        int u = last, v = sta[i];
        printf("从%d: %s 到%d: %s\n", u, place[u].c_str(), v, place[v].c_str());
        last = v;
    }
    printf("总路程为：%d\n", dis[t]);
    return 0;
}