【HDOJ】3311 Dig The Wells

Steiner Tree。概念就不讲了，引入0号结点。[1, n+m]到0连一条边，权重表示挖井的费用。这样建图spfa求MST即满足所求解。

  1 /* 3311 */
  2 #include <iostream>
  3 #include <string>
  4 #include <map>
  5 #include <queue>
  6 #include <set>
  7 #include <stack>
  8 #include <vector>
  9 #include <deque>
 10 #include <algorithm>
 11 #include <cstdio>
 12 #include <cmath>
 13 #include <ctime>
 14 #include <cstring>
 15 #include <climits>
 16 #include <cctype>
 17 #include <cassert>
 18 #include <functional>
 19 #include <iterator>
 20 #include <iomanip>
 21 using namespace std;
 22 //#pragma comment(linker,"/STACK:102400000,1024000")
 23 
 24 #define sti                set<int>
 25 #define stpii            set<pair<int, int> >
 26 #define mpii            map<int,int>
 27 #define vi                vector<int>
 28 #define pii                pair<int,int>
 29 #define vpii            vector<pair<int,int> >
 30 #define rep(i, a, n)     for (int i=a;i<n;++i)
 31 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 32 #define clr                clear
 33 #define pb                 push_back
 34 #define mp                 make_pair
 35 #define fir                first
 36 #define sec                second
 37 #define all(x)             (x).begin(),(x).end()
 38 #define SZ(x)             ((int)(x).size())
 39 #define lson            l, mid, rt<<1
 40 #define rson            mid+1, r, rt<<1|1
 41 
 42 typedef struct {
 43     int v, w, nxt;
 44 } edge_t;
 45 
 46 const int INF = 0x3f3f3f3f;
 47 const int maxst = 65;
 48 const int maxn = 1010;
 49 const int maxe = 13005;
 50 edge_t E[maxe];
 51 int head[maxn], l;
 52 int dp[maxn][maxst];
 53 bool visit[maxn][maxst];
 54 int n, m;
 55 queue<pii> Q;
 56 
 57 void init() {
 58     l = 0;
 59     memset(head, -1, sizeof(head));
 60     memset(dp, INF, sizeof(dp));
 61     memset(visit, false, sizeof(visit));
 62 }
 63 
 64 void addEdge(int u, int v, int w) {
 65     E[l].v = v;
 66     E[l].w = w;
 67     E[l].nxt = head[u];
 68     head[u] = l++;
 69     
 70     E[l].v = u;
 71     E[l].w = w;
 72     E[l].nxt = head[v];
 73     head[v] = l++;
 74 }
 75 
 76 void spfa() {
 77     int u, v, st, nst;
 78     
 79     while (!Q.empty()) {
 80         u = Q.front().fir;
 81         st = Q.front().sec;
 82         visit[u][st] = false;
 83         Q.pop();
 84         for (int i=head[u]; i!=-1; i=E[i].nxt) {
 85             v = E[i].v;
 86             nst = st;
 87             if (v <= n)
 88                 nst |= (1<<v);
 89             if (dp[u][st]+E[i].w < dp[v][nst]) {
 90                 dp[v][nst] = dp[u][st]+E[i].w;
 91                 if (nst==st && !visit[v][nst]) {
 92                     visit[v][nst] = true;
 93                     Q.push(mp(v, nst));
 94                 }
 95             }
 96         }
 97     }
 98 }
 99 
100 void solve() {
101     int mst = 1<<(n+1);
102     int nn = n + m + 1;
103     int kk, kk_;
104     
105     rep(i, 0, n+1)
106         dp[i][1<<i] = 0;
107     
108     rep(i, 0, mst) {
109         rep(j, 0, nn) {
110             rep(k, 1, i) {
111                 if ((k|i) == i) {
112                     kk = k;
113                     kk_ = i - k;
114                     if (j <= n) {
115                         kk |= (1<<j);
116                         kk_ |= (1<<j);
117                     }
118                     dp[j][i] = min(dp[j][i], dp[j][kk]+dp[j][kk_]);
119                 }
120             }
121             if (dp[j][i] != INF) {
122                 Q.push(mp(j, i));
123                 visit[j][i] = true;
124             }
125         }
126         spfa();
127     }
128     
129     int ans = INF;
130     rep(j, 0, nn)
131         ans = min(ans, dp[j][mst-1]);
132     printf("%d\n", ans);
133 }
134 
135 int main() {
136     ios::sync_with_stdio(false);
137     #ifndef ONLINE_JUDGE
138         freopen("data.in", "r", stdin);
139         freopen("data.out", "w", stdout);
140     #endif
141     
142     int p;
143     int u, v, w;
144     
145     while (scanf("%d %d %d",&n,&m,&p)!=EOF) {
146         init();
147         rep(i, 1, n+m+1) {
148             scanf("%d", &w);
149             addEdge(0, i, w);
150         }
151         rep(i, 0, p) {
152             scanf("%d %d %d", &u, &v, &w);
153             addEdge(u, v, w);
154         }
155         solve();
156     }
157     
158     #ifndef ONLINE_JUDGE
159         printf("time = %d.\n", (int)clock());
160     #endif
161     
162     return 0;
163 }

 

转载于:https://www.cnblogs.com/bombe1013/p/5065332.html