PAT All Roads Lead to Rome 单源最短路

思路：单源最短路末班就好了，字符串映射成数字处理。

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AC代码

//#define LOCAL#include <stdio.h>#include <string.h>#include <algorithm>#include <queue>#include <map>#include <vector>#include <string>using namespace std;#define inf 0x3f3f3f3fconst int maxn = 200;map<string, int> ha;int id, st, ed;int n, k;int hap[maxn];char names[maxn][50];int getId(string s) {    if(!ha.count(s)) {        ha[s] = id++;    }    return ha[s];}struct Edge {    int from, to, dist;    Edge(int u, int v, int d):from(u),to(v),dist(d) {}};vector<Edge> edges;vector<int> G[maxn];bool done[maxn];int d[maxn], hp[maxn], pt[maxn], routes[maxn]; //Bestint p[maxn];void init() {    ha.clear();    id = 0;    for(int i = 0; i < maxn; i++) G[i].clear();    edges.clear();}void addEdge(int from, int to, int dist) {    edges.push_back(Edge(from, to, dist));    int m = edges.size();    G[from].push_back(m-1);}struct HeapNode{    int d, u;    HeapNode(int d, int u):d(d), u(u){    }    bool operator < (const HeapNode& rhs) const {        return d > rhs.d;    }};//距离小，开心多，平均大void dijkstra(int s) {    memset(done, 0, sizeof(done));    priority_queue<HeapNode> Q;    for(int i = 0; i < n; i++) {        d[i] = inf;        hp[i] = -inf;        pt[i] = inf;    }    d[s] = hp[s] = pt[s] = 0;    routes[s] = 1;    Q.push(HeapNode(0, s));    while(!Q.empty()) {        HeapNode x = Q.top(); Q.pop();        int u = x.u;        if(done[u]) continue;        done[u] = true;        for(int i = 0; i < G[u].size(); i++) {            Edge& e = edges[G[u][i]];            bool update = false;            if(d[e.to] > d[u] + e.dist) {                routes[e.to] = routes[u];                update = true;            } else if(d[e.to] == d[u] + e.dist) {                routes[e.to] += routes[u];                if(hp[e.to] < hp[u] + hap[e.to]) {                    update = true;                } else if(hp[e.to] == hp[u] + hap[e.to]) {                    if(pt[e.to] > pt[u] + 1) {                        update = true;                    }                }            }            if(update) {                d[e.to] = d[u] + e.dist;                p[e.to] = u;                hp[e.to] = hp[u] + hap[e.to];                pt[e.to] = pt[u] + 1;                Q.push(HeapNode(d[e.to], e.to));            }        }    }}void print(int u) {    if(u == 0) {        printf("%s", names[0]);        return;    } else {        print(p[u]);        printf("->%s", names[u]);    }}int main() {#ifdef LOCAL    freopen("data.in", "r", stdin);    freopen("data.out", "w", stdout);#endif    while(scanf("%d%d%s", &n, &k, names[0]) == 3) {        init();        st = getId(names[0]);        int happy;        for(int i = 1; i < n; i++) {            scanf("%s %d", names[i], &happy);            int u = getId(names[i]);            hap[u] = happy;        }        ed = getId("ROM");        char x[50], y[50];        int u, v, cost;        for(int i = 0; i < k; i++) {            scanf("%s%s%d", x, y, &cost);            u = getId(x), v = getId(y);            //printf("%d %d\n", u, v);            addEdge(u, v, cost);            addEdge(v, u, cost);        }        dijkstra(0);        printf("%d %d %d %d\n", routes[ed], d[ed], hp[ed], (int)(hp[ed]/pt[ed]));        print(ed);        printf("\n");    }    return 0;}

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