HDU-4360 As long as Binbin loves Sangsang

记录每个节点从四个方向来的最优值，用了那个spfa后，因为要标记入队，所以就会牵涉到一个节点的自环现象，所以这里就直接在队列里面记录其当前距离，不进行队列优化，也过了。该题的边竟然是双向的。

代码如下：

#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <queue>
using namespace std;

typedef long long int Int64;

int N, M, idx, mp[255], head[1500], step[1500][4];

Int64 dis[1500][4]; // 保留四状态的最短路

struct Edge
{
    int v, d, k, next;
}e[30000];

struct Node
{
    int v, k, step;
    Int64 dis;
}info, pos;

void addEdge(int x, int y, int d, int k)
{
    ++idx;
    e[idx].v = y, e[idx].d = d, e[idx].k = k;
    e[idx].next = head[x];
    head[x] = idx;
}

void spfa()
{
    int v;
    queue<Node>q;
    memset(dis, 0x3f, sizeof (dis));
    memset(step, 0, sizeof (step));
    info.dis = 0, info.v = 1, info.k = 3;
    info.step = 0;
    q.push(info);
    while (!q.empty()) {
        pos = q.front();
        q.pop();
        for (int i = head[pos.v]; i != -1; i = e[i].next) {
            int k = (pos.k + 1) % 4;
            v = e[i].v;
            if (e[i].k == k) {
                if (dis[v][k] > pos.dis + e[i].d || dis[v][k] == pos.dis + e[i].d && step[v][k] < pos.step + 1) {
                    dis[v][k] = pos.dis + e[i].d;
                    step[v][k] = pos.step + 1;
                    info.v = v, info.dis = dis[v][k];
                    info.k = k, info.step = step[v][k];
                    q.push(info);
                }
            }
        }
    }
    if (dis[N][3] == dis[N+1][0]) { // 没有更改过
        puts("Binbin you disappoint Sangsang again, damn it!");
    }
    else {
        printf("Cute Sangsang, Binbin will come with a donkey after travelling %I64d meters and finding %d LOVE strings at last.\n", dis[N][3], step[N][3]/4);    
    }
}

int main()
{
    int T, x, y, d, ca = 0;
    char s[5];
    mp['L'] = 0, mp['O'] = 1, mp['V'] = 2, mp['E'] = 3;
    scanf("%d", &T);
    while (T--) {
        memset(head, 0xff, sizeof (head));
        idx = -1;
        scanf("%d %d", &N, &M);
        for (int i = 0; i < M; ++i) {
            scanf("%d %d %d %s", &x, &y, &d, s);
            addEdge(x, y, d, mp[s[0]]); // 保留所有的边信息
            addEdge(y, x, d, mp[s[0]]);
            // 自身结点也可以成环 
        }
        printf("Case %d: ", ++ca);
        spfa();
    }
    return 0;
}