wenbao与最短路dij
-----------------------
http://acm.hdu.edu.cn/showproblem.php?pid=1874
裸题
1 #include <stdio.h> 2 #include <string.h> 3 #include <algorithm> 4 using namespace std; 5 6 #define N 10000000 7 int road[200][200], vis[200]; 8 int dij[200], n, m, start, l; 9 10 void Dij(){ 11 int i, j, k, v, path; 12 memset(vis, 0, sizeof(vis)); 13 for(i = 0; i < n; i++) dij[i]=road[start][i]; 14 dij[start] = 0; 15 vis[start] = 1; 16 for(i = 0; i < n; i++){ 17 path = N; 18 for(j = 0; j < n; j++){ 19 if(!vis[j] && path > dij[j]){ 20 path = dij[j]; 21 v = j; 22 } 23 } 24 vis[v] = 1; 25 for(k = 0; k < n; k++){ 26 if(!vis[k]) dij[k] = min(dij[k], dij[v]+road[v][k]); 27 } 28 } 29 } 30 31 int main(){ 32 int i, j, a, b, c; 33 while(scanf("%d%d", &n, &m) != EOF){ 34 for(i = 0; i < n; i++){ 35 for(j = 0; j < n; j++){ 36 if(i==j) road[i][j] = road[j][i] = 0; 37 else road[i][j] = road[j][i] = N; 38 } 39 } 40 for(i = 0; i < m; i++){ 41 scanf("%d%d%d", &a, &b, &c); 42 road[a][b] = road[b][a] = min(road[a][b], c); 43 } 44 scanf("%d%d", &start, &l); 45 Dij(); 46 if(dij[l] < N) printf("%d\n", dij[l]); 47 else printf("-1\n"); 48 } 49 return 0; 50 }
优先队列优化
1 #include <iostream> 2 #include <string.h> 3 #include <queue> 4 #include <vector> 5 using namespace std; 6 7 const int INF = 1e9; 8 const int maxn = 209; 9 const int maxr = 2009; 10 bool vis[maxn]; 11 int dis[maxn], to[maxr], w[maxr], p[maxn], pre[maxr], index; 12 13 struct Node{ 14 int x, y; 15 bool friend operator < (Node a, Node b){ 16 if(a.y == b.y) return a.x < b.x; 17 return a.y > b.y; 18 } 19 }; 20 21 void init(int x){ 22 index = 1; 23 for(int i = 0; i <= x; ++i){ 24 vis[i] = false, dis[i] = INF; 25 p[i] = 0; 26 } 27 } 28 29 void Dij(int sta, int end){ 30 priority_queue<Node> pq; 31 Node a, b; 32 a.x = sta, a.y = 0; 33 dis[sta] = 0; 34 pq.push(a); 35 while(!pq.empty()){ 36 b = pq.top(); pq.pop(); 37 int xx = b.x; 38 if(vis[xx]) continue; 39 vis[xx] = true; 40 for(int i = p[xx]; i; i = pre[i]){ 41 int xxx = to[i]; 42 if(!vis[xxx] && dis[xxx] > dis[xx] + w[i]){ 43 dis[xxx] = dis[xx] + w[i]; 44 a.x = xxx, a.y = dis[xxx]; 45 pq.push(a); 46 } 47 } 48 } 49 printf("%d\n", dis[end] == INF ? -1 : dis[end]); 50 } 51 52 int main(){ 53 int n, m, s, t, x, y, z; 54 while(~scanf("%d%d", &n, &m)){ 55 init(n); 56 while(m--){ 57 scanf("%d%d%d", &x, &y, &z); 58 to[index] = y, w[index] = z, pre[index] = p[x], p[x] = index++; 59 to[index] = x, w[index] = z, pre[index] = p[y], p[y] = index++; 60 } 61 scanf("%d%d", &s, &t); 62 Dij(s, t); 63 } 64 return 0; 65 }
---------------------------
升级版
http://acm.hdu.edu.cn/showproblem.php?pid=3790
1 #include <iostream> 2 #include <string.h> 3 #include <stdio.h> 4 using namespace std; 5 6 #define INF 0xfffffff 7 #define maxn 1000 8 9 int road[1000][1000], dij[maxn], money[1000][1000], dijm[maxn]; 10 bool flag[maxn]; 11 12 void Dij(int start, int endn, int n){ 13 memset(flag, 0, sizeof(flag)); 14 int path, v; 15 for(int i = 1; i <= n; i++){ 16 dij[i] = road[start][i]; 17 dijm[i] = money[start][i]; 18 } 19 flag[start] = 1; 20 dij[start] = 0; 21 for(int i = 1; i <= n; i++){ 22 path = INF; 23 for(int j = 1; j <= n; j++){ 24 if(!flag[j] && path > dij[j]){ 25 path = dij[j]; 26 v = j; 27 } 28 } 29 flag[v] = 1; 30 for(int k = 1; k <= n; k++){ 31 if(!flag[k]){ 32 if(dij[k] == dij[v] + road[v][k]){ 33 if(dijm[k] > dijm[v] + money[v][k]){ 34 dij[k] = dij[v] + road[v][k]; 35 dijm[k] = dijm[v] + money[v][k]; 36 } 37 } 38 else if(dij[k] > dij[v] + road[v][k]){ 39 dij[k] = dij[v] + road[v][k]; 40 dijm[k] = dijm[v] + money[v][k]; 41 } 42 } 43 } 44 } 45 } 46 47 int main(){ 48 int a, b, c, d, start, endn, n, m; 49 while(scanf("%d%d", &n, &m), n+m){ 50 for(int i = 1; i <= n; i++){ 51 for( int j = 1; j < i; j++){ 52 road[i][j]=road[j][i]= money[i][j]=money[j][i]=INF; 53 } 54 } 55 for(int i = 0; i < m ; i++){ 56 scanf("%d%d%d%d", &a, &b, &c, &d); 57 if(road[a][b] > c){ 58 road[a][b] = road[b][a] = c; 59 money[a][b] = money[b][a] = d; 60 } 61 } 62 scanf("%d%d", &start, &endn); 63 Dij(start, endn, n); 64 printf("%d %d\n",dij[endn], dijm[endn]); 65 } 66 return 0; 67 }
-----------------------------
邻接表加队列优化
1 const int maxn = 1e5+10; 2 bool vis[maxn]; 3 int dis[maxn]; 4 vector<int> vv[maxn]; 5 vector<int> v[maxn]; 6 7 struct Node{ 8 int x, y; 9 bool friend operator < (Node a, Node b){ 10 if(a.y == b.y) return a.x < b.x; 11 return a.y < b.y; //从大到小 12 } 13 }; 14 15 void Dij(int sta, int end){ 16 memset(vis, false, sizeof(vis)); 17 memset(dis, -1, sizeof(dis));//memset(dis, 0x3f, sizeof(dis)); 18 priority_queue<Node> pq; 19 Node a, b; 20 a.x = sta, a.y = 0;//a,y = 0x3f; 21 dis[sta] = 0; // dis[sta] = 0x3f3f3f3f; 22 pq.push(a); 23 while(!pq.empty()){ 24 b = pq.top(); pq.pop(); 25 int xx = b.x; 26 if(vis[xx]) continue; 27 vis[xx] = true; 28 for(int i = 0; i < v[xx].size(); i++){ 29 int xxx = v[xx][i]; 30 if(!vis[xxx] && dis[xxx] > dis[xx] + vv[xx][i]){ 31 dis[xxx] = dis[xx] + vv[xx][i]; 32 a.x = xxx, a.y = dis[xxx]; 33 pq.push(a); 34 } 35 } 36 } 37 printf("%d\n", dis[end]); 38 }
离散课本实现
1 #include <bits/stdc++.h> 2 using namespace std; 3 const int maxn = 0x3f3f3f3f; 4 int a[20][20], dis[20], n, m, b[20]; 5 bool vis[20]; 6 void dij(){ 7 for(int i = 2; i <= n; i++){ 8 dis[i] = maxn, b[i] = i; 9 } 10 vis[1] = true, dis[1] = 0, b[1] = 1; 11 int x = 1; 12 for(int j = 0; j < n; j++){ 13 for(int i = 1; i <= n; i++){ 14 if(!vis[i] && dis[x] + a[x][i] < dis[i]){ 15 dis[i] = dis[x] + a[x][i], b[i] = x; 16 } 17 } 18 int mi = maxn+1; 19 for(int k = 1; k <= n; k++){ 20 if(!vis[k] && dis[k] < mi){ 21 mi = dis[k], x = k; 22 } 23 } 24 vis[x] = true; 25 } 26 } 27 int main(){ 28 scanf("%d%d", &n, &m); 29 for(int i = 1; i <= n; i++){ 30 for(int j = 1; j <= n; j++){ 31 a[i][j] = maxn; 32 } 33 } 34 for(int i = 0; i < m; i++){ 35 int x, y, z; 36 scanf("%d%d%d", &x, &y, &z); 37 a[x][y] = a[y][x] = z; 38 } 39 dij(); 40 for(int i = 1; i <= n; i++){ 41 printf("%d**********%d\n", dis[i], b[i]); 42 } 43 return 0; 44 }
只有不断学习才能进步！
