【斯坦纳树】 HDOJ 4085 Peach Blossom Spring

额。。。斯坦纳树参见：http://endlesscount.blog.163.com/blog/static/821197872012525113427573

#include <iostream>#include <queue> #include <stack> #include <map> #include <set> #include <bitset> #include <cstdio> #include <algorithm> #include <cstring> #include <climits>#include <cstdlib>#include <cmath>#include <time.h>#define maxn 2005#define maxm 4005#define eps 1e-7#define mod 1000000007#define INF 0x3f3f3f3f#define PI (acos(-1.0))#define lowbit(x) (x&(-x))#define mp make_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid #define rson o<<1 | 1, mid+1, R#define pii pair<int, int>#pragma comment(linker, "/STACK:16777216")typedef long long LL;typedef unsigned long long ULL;//typedef int LL;using namespace std;LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}// headstruct Edge{int v, w;Edge *next;}*H[maxn], E[maxm], *edges;queue<pair<int, int> > q;bool in[55][maxn];int d[55][maxn];int dp[maxn];int p[55];int n, m, k, o;void addedges(int u, int v, int w){edges->v = v;edges->w = w;edges->next = H[u];H[u] = edges++;}void init(){edges = E;memset(H, 0, sizeof H);memset(p, 0, sizeof p);memset(in, 0, sizeof in);memset(d, INF, sizeof d);memset(dp, INF, sizeof dp);}void read(){int u, v, w;scanf("%d%d%d", &n, &m, &k);while(m--) {scanf("%d%d%d", &u, &v, &w);addedges(u, v, w);addedges(v, u, w);}for(int i = 1; i <= k; i++) {p[i] = 1 << i - 1;p[n-i+1] = 1 << k + i - 1;d[i][p[i]] = d[n-i+1][p[n-i+1]] = 0;}o = 1 << k * 2;}bool update(int x, int y, int w){if(d[x][y] > w) {d[x][y] = w;return true;}else return false;}bool check(int x){int res = 0;for(int i = 0; x; x >>= 1, i++)res += (x & 1) * (i < k ? 1 : -1);return res == 0;}void spfa(){while(!q.empty()) {int x = q.front().first, y = q.front().second;q.pop(), in[x][y] = false;for(Edge *e = H[x]; e; e = e->next) {int v = e->v, w = e->w;if(update(v, y | p[v], w + d[x][y]) && !in[v][y]) {in[v][y] = true;q.push(mp(v, y));}}}}void work(){for(int y = 0; y < o; y++) {for(int x = 1; x <= n; x++) {for(int i = (y - 1) & y; i; i = (i - 1) & y)d[x][y] = min(d[x][y], d[x][i | p[x]] + d[x][y - i | p[x]]);if(d[x][y] < INF) q.push(mp(x, y)), in[x][y] = true;}spfa();}for(int i = 0; i < o; i++) {for(int j = 1; j <= n; j++)dp[i] = min(dp[i], d[j][i]);}for(int i = 0; i < o; i++)if(check(i))for(int j = (i - 1) & i; j; j = (j - 1) & i)if(check(j))dp[i] = min(dp[i], dp[i - j] + dp[j]);if(dp[o-1] == INF) printf("No solution\n");else printf("%d\n", dp[o-1]);}int main(){int _;while(scanf("%d", &_)!=EOF) {while(_--) {init();read();work();}}return 0;}