hdoj 2112 HDU Today【3种方法】

HDU Today

Time Limit: 15000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 21773    Accepted Submission(s): 5216

Problem Description

经过锦囊相助，海东集团终于度过了危机，从此，HDU的发展就一直顺风顺水，到了2050年，集团已经相当规模了，据说进入了钱江肉丝经济开发区500强。这时候，XHD夫妇也退居了二线，并在风景秀美的诸暨市浬浦镇陶姚村买了个房子，开始安度晚年了。
这样住了一段时间，徐总对当地的交通还是不太了解。有时很郁闷，想去一个地方又不知道应该乘什么公交车，在什么地方转车，在什么地方下车（其实徐总自己有车，却一定要与民同乐，这就是徐总的性格）。
徐总经常会问蹩脚的英文问路：“Can you help me?”。看着他那迷茫而又无助的眼神，热心的你能帮帮他吗？
请帮助他用最短的时间到达目的地（假设每一路公交车都只在起点站和终点站停，而且随时都会开）。

 

Input

输入数据有多组，每组的第一行是公交车的总数N(0<=N<=10000)；
第二行有徐总的所在地start，他的目的地end；
接着有n行，每行有站名s，站名e，以及从s到e的时间整数t(0<t<100)(每个地名是一个长度不超过30的字符串)。
note：一组数据中地名数不会超过150个。
如果N==-1，表示输入结束。

 

Output

如果徐总能到达目的地，输出最短的时间；否则，输出“-1”。

 

Sample Input

6xiasha westlakexiasha station 60xiasha ShoppingCenterofHangZhou 30station westlake 20ShoppingCenterofHangZhou supermarket 10xiasha supermarket 50supermarket westlake 10-1

 

Sample Output

50Hint:The best route is:xiasha->ShoppingCenterofHangZhou->supermarket->westlake虽然偶尔会迷路，但是因为有了你的帮助**和**从此还是过上了幸福的生活。――全剧终――

 

spfa一开始把函数写外边老WA.....

dijkstra：

#include<cstdio>#include<cstring>#include<cmath>#define Wi(a) while(a--)#define Si(a) scanf("%d", &a)#define Sch(a) scanf("%s", a)#define Pi(a) printf("%d\n", (a))#define mem(a, b) memset(a, (b), sizeof(a))#define INF 0x3f3f3f#include<algorithm>using namespace std;const int mx = 200;int map[mx][mx], dis[mx], vis[mx];char now[33], to[33], str[mx][33];int n, N;int s, t;void init(){for(int i = 0; i < mx; i++){for(int j = 0; j < mx; j++)map[i][j] = i==j?0:INF;}}int turn(char s[]){for(int i = 1; i <= n; i++){if(strcmp(s, str[i])==0)return i;}strcpy(str[++n], s);return n;}void dijkstra(int s){mem(vis, 0);int i, j;for(i = 1; i <= n; i++)   dis[i] = map[s][i];vis[s] = 1;for(i = 1; i < n; i++){int minn = INF, k = s;for(j = 1; j <= n; j++){if(!vis[j] && dis[j] < minn){minn = dis[j];k = j;}}vis[k] = 1;for(j = 1; j <= n; j++){if(!vis[j])   dis[j] = min(dis[j], dis[k]+map[k][j]);}}if(dis[t] != INF)Pi(dis[t]);else if(s == t)puts("0");elseputs("-1");}int main(){while(Si(N)==1, N != -1){init();   n = 0;Sch(now); s = turn(now);Sch(to);  t = turn(to);int a, b, c;Wi(N){Sch(now); Sch(to); Si(c);a = turn(now);  b = turn(to);if(map[a][b] > c)map[a][b] = map[b][a] = c;}dijkstra(s);}return 0;}

写完dijkstra再写floyd感觉轻松许多~

floyd：

#include<cstdio>#include<cstring>#include<cmath>#define Wi(a) while(a--)#define Si(a) scanf("%d", &a)#define Sch(a) scanf("%s", a)#define Pi(a) printf("%d\n", (a))#define mem(a, b) memset(a, (b), sizeof(a))#define INF 0x3f3f3f#include<algorithm>using namespace std;const int mx = 200;int map[mx][mx], dis[mx], vis[mx];char now[33], to[33], str[mx][33];int n, N;int s, t;void init(){for(int i = 0; i < mx; i++){for(int j = 0; j < mx; j++)map[i][j] = i==j?0:INF;}}int turn(char *s){for(int i = 1; i <= n; i++){if(strcmp(s, str[i])==0)return i;}strcpy(str[++n], s);return n;}void floyd(){int i, j, k;for(k = 0; k <= n; k++){for(i = 0; i <= n; i++){for(j = 0; j <= n; j++)map[i][j] = min(map[i][j], map[i][k]+map[k][j]);}}if(map[s][t] != INF)Pi(map[s][t]);else if(s == t)puts("0");elseputs("-1");}int main(){while(Si(N)==1, N != -1){init();   n = 0;Sch(now); s = turn(now);Sch(to);  t = turn(to);int a, b, c;Wi(N){Sch(now); Sch(to); Si(c);a = turn(now);  b = turn(to);if(map[a][b] > c)map[a][b] = map[b][a] = c;}floyd();}return 0;}

spfa：

#include<cstdio>#include<cstring>#include<cmath>#include<queue>#define Wi(a) while(a--)#define Si(a) scanf("%d", &a)#define Sch(a) scanf("%s", a)#define Pi(a) printf("%d\n", (a))#define mem(a, b) memset(a, (b), sizeof(a))#define INF 0x3f3f3f3f #include<algorithm>using namespace std;const int mx = 1010;int dis[mx], vis[mx], head[mx];int  edgenum, n, m;char str[mx][mx];int find(char ch[]){for(int i = 1; i <= n; i++){if(strcmp(ch, str[i])==0)return i;}strcpy(str[++n], ch);return n;}struct node{int from, to, val, next;};node edge[211000];void init(){n = 0;edgenum = 0;mem(str, '\0');mem(head, -1);}void add(int a, int b, int c){node E = {a, b, c, head[a] };edge[edgenum] = E;head[a] = edgenum++;}void spfa(int s, int t){queue<int> q;mem(dis, INF);  mem(vis, 0);dis[s] = 0;vis[s] = 1;q.push(s);while(!q.empty()){int u = q.front();  q.pop();  vis[u] = 0;for(int i = head[u]; i != -1; i = edge[i].next){int v = edge[i].to;if(dis[v] > dis[u]+edge[i].val){dis[v] = dis[u]+edge[i].val;if(!vis[v]){vis[v] = 1;q.push(v);}}}}if(dis[t] != INF)Pi(dis[t]);elseprintf("-1\n");}char s1[33],s2[33];void getmap(){int a, b, c;Wi(m){Sch(s1);a = find(s1);Sch(s2);b = find(s2);Si(c);add(a, b, c);add(b, a, c);}}int main(){while(Si(m)==1, m!=-1){init();Sch(s1);int ss = find(s1);Sch(s2);int tt = find(s2);getmap();spfa(ss, tt);}return 0;}