poj 1724ROADS（bfs和dfs做法） 

 1 /*
 2 dfs比较好想，就是测试数据的问题，导致在遍历边的时候要倒着遍历才过！
 3 */
 4 #include<iostream> 
 5 #include<cstdio>
 6 #include<cstring>
 7 #include<vector>
 8 #include<algorithm>
 9 #define Max 0x3f3f3f3f
10 using namespace std;
11 
12 struct node{
13    int D;
14    int L, T;
15    node(int D, int L, int T){
16       this->D=D;
17       this->L=L;
18       this->T=T;
19    }
20    node(){
21    }
22 };
23 
24 node v[105][1000];
25 int cnt[105];
26 int vis[105];
27 
28 int maxCost, R, N, S, D, L, T;
29 int cost, dist;
30 
31 void dfs(int cur, int d, int c){
32    int i;
33    if(cur == N){
34        if(dist>d){
35           dist=d;
36           if(cost>c)  cost=c;
37        }
38        return ;
39    }
40    for(i=cnt[cur]-1; i>=0; --i)
41       if(!vis[v[cur][i].D] &&  c+v[cur][i].T<=maxCost && d+v[cur][i].L<dist){
42          vis[v[cur][i].D]=1;
43          dfs(v[cur][i].D, d+v[cur][i].L, c+v[cur][i].T);
44          vis[v[cur][i].D]=0;
45       }
46 }
47 
48 int main(){
49    while(scanf("%d", &maxCost)!=EOF){
50        scanf("%d%d", &N, &R);
51        memset(cnt, 0, sizeof(cnt));
52        while(R--){
53           scanf("%d%d%d%d", &S, &D, &L, &T);
54           v[S][cnt[S]++]=node(D, L, T);
55        }
56        cost=dist=Max;
57        memset(vis, 0, sizeof(vis));
58        dfs(1, 0, 0);
59        if(cost<=maxCost)
60           printf("%d\n", dist);
61        else printf("-1\n");
62    }
63    return 0;
64 }
 1 /*
 2   spfa + 01背包 
 3   dist[next][j]=min(dist[cur][j-v[cur][i].T]+v[cur][i].L) j={v[cur][i].T。。。maxCost}
 4   一维数组表示的是城市节点，二维表示的当前费用
 5   dist[i][j]表示经过i城市，费用为j时总的路径长度！ 
 6 */
 7 #include<iostream> 
 8 #include<cstdio>
 9 #include<cstring>
10 #include<vector>
11 #include<queue>
12 #include<algorithm>
13 #define Max 0x3f3f3f3f
14 using namespace std;
15 
16 struct node{
17    int D;
18    int L, T;
19    node(int D, int L, int T){
20       this->D=D;
21       this->L=L;
22       this->T=T;
23    }
24    node(){
25    }
26 };
27 
28 node v[105][1000];
29 int cnt[105];
30 int dist[105][10005];
31 int vis[105];
32 queue<int>q;
33 int maxCost, R, N, S, D, L, T;
34 
35 int spfa(){
36    int i;
37    while(!q.empty()){
38        int cur = q.front();
39        q.pop();
40        vis[cur]=0;
41        for(i=0; i<cnt[cur]; ++i){
42            int next=v[cur][i].D;
43            for(int j=v[cur][i].T; j<=maxCost; ++j)
44               if(dist[next][j]>dist[cur][j-v[cur][i].T]+v[cur][i].L){
45                  dist[next][j]=dist[cur][j-v[cur][i].T]+v[cur][i].L;
46                  if(!vis[next]){
47                    vis[next]=1;
48                    q.push(next);
49                  }
50              }
51        }
52    }
53 }
54 
55 void bfs(int cur){
56    q.push(1);
57    memset(dist, 0x3f, sizeof(dist));
58    for(int i=0; i<105; ++i)
59       dist[1][i]=0;
60    vis[1]=1;
61    spfa();
62 }
63 
64 int main(){
65    while(scanf("%d", &maxCost)!=EOF){
66        scanf("%d%d", &N, &R);
67        memset(cnt, 0, sizeof(cnt));
68        while(R--){
69           scanf("%d%d%d%d", &S, &D, &L, &T);
70           v[S][cnt[S]++]=node(D, L, T);
71        }
72        memset(vis, 0, sizeof(vis));
73        bfs(1);
74        int minDist=Max;
75        for(int i=1; i<=maxCost; ++i)
76           if(minDist>dist[N][i])
77               minDist=dist[N][i];
78        if(minDist!=Max)
79           printf("%d\n", minDist);
80        else printf("-1\n");
81    }
82    return 0;
83 }

 

 

 

posted @ 2014-07-28 21:59  hjzqyx  阅读(377)  评论(0)  编辑  收藏  举报