宽搜+剪枝，不是说好了适用于稀疏矩阵的嘛，怎么题目的测试数据边数达到10^6。。。不科学
代码：
1 #include <iostream> 2 #include <cstring> 3 #include <map> 4 5 using namespace std; 6 7 #define MAX_POINT 100008 8 #define MAX_EDGE 1000008 9 10 int N, M, S, T; 11 int p[MAX_POINT]; 12 int q[MAX_POINT]; 13 int d[MAX_POINT]; 14 map<int, map<int, int> > g; 15 int head, tail; 16 17 void spfa() { 18 for (int i = 0; i < N; i++) 19 p[i] = -1; 20 memset(d, 1, sizeof(d)); 21 head = tail = 0; 22 d[S] = 0; 23 p[S] = tail; 24 q[tail++] = S; 25 26 while (head < tail) { 27 int s = q[head++]; 28 for (auto t : g[s]) { 29 int len = d[s] + t.second; 30 if (len < d[t.first]) { 31 d[t.first] = len; 32 if (p[t.first] < 0) { 33 p[t.first] = tail; 34 q[tail++] = t.first; 35 } 36 } 37 } 38 p[s] = -1; 39 } 40 } 41 42 int main() { 43 scanf("%d%d%d%d", &N, &M, &S, &T); 44 for (int i = 0; i < M; i++) { 45 int a, b, len; 46 scanf("%d%d%d", &a, &b, &len); 47 if (!g[a][b]) 48 g[a][b] = g[b][a] = len; 49 else 50 g[a][b] = g[b][a] = min(g[a][b], len); 51 } 52 53 spfa(); 54 55 printf("%d ", d[T]); 56 57 return 0; 58 }