DP/最短路 URAL 1741 Communication Fiend

 

题目传送门

 1 /*  2  题意：程序从1到n版本升级，正版+正版->正版，正版+盗版->盗版，盗版+盗版->盗版  3  正版+破解版->正版，盗版+破解版->盗版  4  DP：每种情况考虑一遍，递推就行了  5  注意：开long long  6 */  7 #include <cstdio>  8 #include <iostream>  9 #include <algorithm> 10 #include <cstring> 11 #include <cmath> 12 using namespace std; 13 14 const int MAXN = 1e4 + 10; 15 const int INF = 0x3f3f3f3f; 16 struct Node 17 { 18 int u, v, w; 19 char s[10]; 20 }node[MAXN]; 21 long long dp[MAXN][2]; 22 23 bool cmp(Node x, Node y) 24 { 25 if (x.u == y.u) return x.v < y.v; 26 return x.u < y.u; 27 } 28 29 int main(void) //URAL 1741 Communication Fiend 30 { 31 //freopen ("T.in", "r", stdin); 32 33 int n, m; 34 while (scanf ("%d%d", &n, &m) == 2) 35  { 36 for (int i=1; i<=m; ++i) 37  { 38 scanf ("%d %d %d %s", &node[i].u, &node[i].v, &node[i].w, &node[i].s); 39  } 40 sort (node+1, node+1+m, cmp); 41 42 memset (dp, -1, sizeof (dp)); 43 dp[1][0] = 0; 44 for (int i=1; i<=m; ++i) 45  { 46 Node a = node[i]; 47 if (a.s[0] == 'L') 48  { 49 if (dp[a.u][0] != -1 && (dp[a.v][0] == -1 || dp[a.v][0] > dp[a.u][0] + a.w)) 50  { 51 dp[a.v][0] = dp[a.u][0] + a.w; 52  } 53  } 54 else if (a.s[0] == 'P') 55  { 56 if (dp[a.u][0] != -1 && (dp[a.v][1] == -1 || dp[a.v][1] > dp[a.u][0] + a.w)) 57  { 58 dp[a.v][1] = dp[a.u][0] + a.w; 59  } 60 if (dp[a.u][1] != -1 && (dp[a.v][1] == -1 || dp[a.v][1] > dp[a.u][1] + a.w)) 61  { 62 dp[a.v][1] = dp[a.u][1] + a.w; 63  } 64  } 65 else if (a.s[0] == 'C') 66  { 67 if (dp[a.u][0] != -1 && (dp[a.v][0] == -1 || dp[a.v][0] > dp[a.u][0] + a.w)) 68  { 69 dp[a.v][0] = dp[a.u][0] + a.w; 70  } 71 if (dp[a.u][1] != -1 && (dp[a.v][1] == -1 || dp[a.v][1] > dp[a.u][1] + a.w)) 72  { 73 dp[a.v][1] = dp[a.u][1] + a.w; 74  } 75  } 76  } 77 78 if (dp[n][0] == -1 && dp[n][1] == -1) puts ("Offline"); 79 else 80  { 81 puts ("Online"); 82 if (dp[n][0] == -1) printf ("%I64d\n", dp[n][1]); 83 else if (dp[n][1] == -1) printf ("%I64d\n", dp[n][0]); 84 else printf ("%I64d\n", min (dp[n][0], dp[n][1])); 85  } 86  } 87 88 return 0; 89 } 90 91 /* 92 Online 93 Offline 94 */

 1 /*

 2  WA了4，5发，第一是抄Kuangbin的模板抄错了；第二是选取的INF值太小了  3  以后学习一下最值的选取的方法:)  4 */

 5 #include <cstdio>

 6 #include <iostream>

 7 #include <algorithm>

 8 #include <cstring>

 9 #include <vector>

 10 #include <cmath>

 11 #include <queue>

 12 using namespace std;  13 

 14 const int MAXN = 1e4 + 10;  15 const int INF = 0x3f3f3f3f;  16 const int INFF = 0x7fffffff;  17 const long long inf = ((long long)1<<50);  18 struct Edge  19 {  20     int v, w;  21     int f;  22     Edge (int _v = 0, int _w = 0, int _f = 0) : v (_v), w (_w), f (_f) {}  23 };  24 bool vis[MAXN];  25 int cnt[MAXN];  26 long long d[MAXN][2];  27 vector<Edge> G[MAXN];  28 int n, m;  29 

 30 void add_edge(int u, int v, int w, int f)  31 {  32  G[u].push_back (Edge (v, w, f));  33 }  34 

 35 bool SPFA(int s)  36 {  37     memset (cnt, 0, sizeof (cnt));  38     memset (vis, false, sizeof (vis));  39     for (int i=1; i<=n; ++i)    d[i][0] = d[i][1] = inf;  40     vis[s] = true;    d[s][0] = 0;    cnt[s] = 1;  41 

 42     queue<int> Q; Q.push (s);  43     while (!Q.empty ())  44  {  45         int u = Q.front (); Q.pop ();  46         vis[u] = false;                        //失误！

 47         for (int i=0; i<G[u].size (); ++i)  48  {  49             int v = G[u][i].v;    int w = G[u][i].w;    int f = G[u][i].f;  50             if (f == 0)  51  {  52                 if (d[v][0] > d[u][0] + w)    d[v][0] = d[u][0] + w;  53  }  54             else if (f == 1)  55  {  56                 if (d[v][1] > d[u][0] + w)    d[v][1] = d[u][0] + w;  57                 if (d[v][1] > d[u][1] + w)    d[v][1] = d[u][1] + w;  58  }  59             else

 60  {  61                 if (d[v][0] > d[u][0] + w)    d[v][0] = d[u][0] + w;  62                 if (d[v][1] > d[u][1] + w)    d[v][1] = d[u][1] + w;  63  }  64             if (!vis[v])  65  {  66                 vis[v] = true; Q.push (v);  67                 if (++cnt[v] > n)    return true;  68  }  69  }  70  }  71 

 72     return false;  73 }  74 

 75 int main(void)        //URAL 1741 Communication Fiend

 76 {  77     //freopen ("T.in", "r", stdin);

 78 

 79     while (scanf ("%d%d", &n, &m) == 2)  80  {  81         for (int i=1; i<=n; ++i) G[i].clear ();  82         for (int i=1; i<=m; ++i)  83  {  84             int u, v, w, f;    char s[10];  85             scanf ("%d %d %d %s", &u, &v, &w, &s);  86             if (s[0] == 'L')    f = 0;  87             else if (s[0] == 'P')    f = 1;  88             else if (s[0] == 'C')    f = -1;  89  add_edge (u, v, w, f);  90  }  91 

 92         if (!SPFA (1))  93  {  94             long long ans = min (d[n][0], d[n][1]);  95             if (ans == inf)    puts ("Offline");  96             else    {puts ("Online");    printf ("%I64d\n", ans);}  97  }  98  }  99 

100     return 0; 101 } 102 

103 /*

104 Online 105 Offline 106 */

SPFA