kuangbin_ShortPathS (POJ 3169)

被cow类题目弄得有些炸裂 想了好久好久写了120多行 依然长跪不起发现计算约束条件的时候还是好多麻烦的地方过不去

然后看了看kuangbin的blog 都是泪啊 差分约束的方式做起来只要70多行啊炒鸡简洁有没有

Ps 给手写queue的实现方式跪一下 真是快的飞起

 1 #include <cstdio>
 2 #include <cmath>
 3 #include <cstring>
 4 #include <queue>
 5 #include <algorithm>
 6 #define INF 0x3F3F3F3F
 7 using namespace std;
 8
 9 const int MAXN = (int)(1e4 + 10);
10 const int MAXM = (int)(1e5 + 10);
11
12 int n, ml, md, dist[MAXN];
13 int size, head[MAXN], point[MAXM], val[MAXM], nxt[MAXM];
14
15 void add (int from, int to, int value)
16 {
17     val[size] = value;
18     point[size] = to;
19     nxt[size] = head[from];
20     head[from] = size++;
21 }
22
23 int  spfa()
24 {
25     int time[MAXN];//也许以后用cnt做名字比较好
26     bool vis[MAXN];
27     queue<int> q;
28     memset(vis, false, sizeof vis);
29     memset(dist, INF, sizeof dist);
30     memset(time, 0, sizeof time);
31
32     q.push(1);
33     vis[1] = true;
34     dist[1] = 0;
35     while(!q.empty()){
36         int u = q.front();
37         q.pop();
38         vis[u] = false;
39         for(int i = head[u]; ~i; i = nxt[i]){
40             if(dist[point[i]] > dist[u] + val[i]){
41                 dist[point[i]] = dist[u] + val[i];
42                 if(!vis[point[i]]){
43                     vis[point[i]] = true;
44                     q.push(point[i]);
45                     if(++time[point[i]] > n) return -1;
46                 }
47             }
48         }
49     }
50     return dist[n] == INF ? -2 : dist[n];
51 }
52
53 int main()
54 {
55     size = 0;
56     memset(head, -1, sizeof head);
57
58     scanf("%d%d%d", &n, &ml, &md);
59     while(ml--){
60         int from, to, value;
61         scanf("%d%d%d", &from, &to, &value);
62         if(from > to) swap(from, to);
63         add(from, to, value);
64     }
65     while(md--){
66         int from, to, value;
67         scanf("%d%d%d", &from, &to, &value);
68         if(from < to) swap(from, to);
69         add(from, to, -value);
70     }
71     int ans = spfa();
72     printf("%d\n", ans);
73     return 0;
74 }