只有一周了QAQ
2.21
CF 629 E Famil Door and Roads
其实Tarjan的时候搞一搞，就O（n+m）了吖。
1 #include <iostream> 2 #include <cstdio> 3 #include <vector> 4 using namespace std; 5 typedef long long LL; 6 typedef pair<int, int> pii; 7 const int maxn = 1e5 + 10; 8 vector<pii> q[maxn]; 9 double ans[maxn]; 10 11 //Tree 12 int cnt, h[maxn]; 13 struct edge 14 { 15 int to, pre; 16 } e[maxn<<1]; 17 18 void add(int from, int to) 19 { 20 cnt++; 21 e[cnt].pre = h[from]; 22 e[cnt].to = to; 23 h[from] = cnt; 24 } 25 26 //TreeDP 27 LL dis[maxn], fdis[maxn]; 28 int sz[maxn], fsz[maxn], dep[maxn]; 29 void dfs1(int p, int d) 30 { 31 sz[p] = 1, dep[p] = d; 32 for(int i = h[p]; i; i = e[i].pre) 33 { 34 int to = e[i].to; 35 if(dep[to]) continue; 36 dfs1(to, d + 1); 37 sz[p] += sz[to]; 38 dis[p] += dis[to] + sz[to]; 39 } 40 } 41 42 //Tarjan 43 int fa[maxn], vis[maxn], cur[maxn]; 44 int Find(int x) 45 { 46 return fa[x] == x ? x : fa[x] = Find(fa[x]); 47 } 48 49 void dfs2(int p, int f) 50 { 51 fa[p] = p, vis[p] = 2; 52 if(p != 1) 53 { 54 fsz[p] = fsz[f] + sz[f] - sz[p]; 55 fdis[p] = fdis[f] + dis[f] - dis[p] - sz[p] + fsz[p]; 56 } 57 for(int i = h[p]; i; i = e[i].pre) 58 { 59 int to = e[i].to; 60 if(to == f) continue; 61 cur[p] = to; 62 dfs2(to, p); 63 fa[to] = p; 64 } 65 vis[p] = 1; 66 int qsz = q[p].size(); 67 for(int i = 0; i < qsz; i++) 68 { 69 int to = q[p][i].first, id = q[p][i].second; 70 if(!vis[to]) continue; 71 int anc = Find(to); 72 if(anc == to) 73 { 74 LL d = dep[p] - dep[to] + 1; 75 ans[id] = (1.0 * dis[p] * fsz[cur[to]] + 1.0 * (fdis[cur[to]] - (LL)fsz[cur[to]]) * sz[p]) / sz[p] / fsz[cur[to]] + d; 76 } 77 else if(vis[p] == 1 && anc != p) 78 { 79 LL d = dep[p] + dep[to] - dep[anc] - dep[anc] + 1; 80 ans[id] = (1.0 * dis[p] * sz[to] + 1.0 * dis[to] * sz[p]) / sz[p] / sz[to] + d; 81 } 82 } 83 return; 84 } 85 86 int main(void) 87 { 88 int n, m; 89 scanf("%d %d", &n, &m); 90 for(int i = 1; i < n; i++) 91 { 92 int u, v; 93 scanf("%d %d", &u, &v); 94 add(u, v), add(v, u); 95 } 96 for(int i = 0; i < m; i++) 97 { 98 int u, v; 99 scanf("%d %d", &u, &v); 100 q[u].push_back(pii(v, i)); 101 q[v].push_back(pii(u, i)); 102 } 103 dfs1(1, 1); 104 dfs2(1, 0); 105 for(int i = 0; i < m; i++) printf("%.9f ", ans[i]); 106 return 0; 107 }
HDU 3605 Escape
原来是状压阿。
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <algorithm> 5 #include <queue> 6 using namespace std; 7 const int INF = 1e9; 8 const int maxn = 2e5 + 10; 9 int lv[maxn], it[maxn]; 10 int cnt, h[maxn]; 11 12 struct edge 13 { 14 int to, pre, cap; 15 } e[maxn<<1]; 16 17 void init() 18 { 19 memset(h, -1, sizeof(h)); 20 cnt = 0; 21 } 22 23 void add(int from, int to, int cap) 24 { 25 e[cnt].pre = h[from]; 26 e[cnt].to = to; 27 e[cnt].cap = cap; 28 h[from] = cnt; 29 cnt++; 30 } 31 32 void ad(int from, int to, int cap) 33 { 34 add(from, to, cap); 35 add(to, from, 0); 36 } 37 38 void bfs(int s) 39 { 40 memset(lv, -1, sizeof(lv)); 41 queue<int> q; 42 lv[s] = 0; 43 q.push(s); 44 while(!q.empty()) 45 { 46 int v = q.front(); q.pop(); 47 for(int i = h[v]; i >= 0; i = e[i].pre) 48 { 49 int cap = e[i].cap, to = e[i].to; 50 if(cap > 0 && lv[to] < 0) 51 { 52 lv[to] = lv[v] + 1; 53 q.push(to); 54 } 55 } 56 } 57 } 58 59 int dfs(int v, int t, int f) 60 { 61 if(v == t) return f; 62 for(int &i = it[v]; i >= 0; i = e[i].pre) 63 { 64 int &cap = e[i].cap, to = e[i].to; 65 if(cap > 0 && lv[v] < lv[to]) 66 { 67 int d = dfs(to, t, min(f, cap)); 68 if(d > 0) 69 { 70 cap -= d; 71 e[i^1].cap += d; 72 return d; 73 } 74 } 75 } 76 return 0; 77 } 78 79 int Dinic(int s, int t) 80 { 81 int flow = 0; 82 while(1) 83 { 84 bfs(s); 85 if(lv[t] < 0) return flow; 86 memcpy(it, h, sizeof(it)); 87 int f; 88 while((f = dfs(s, t, INF)) > 0) flow += f; 89 } 90 } 91 92 int peo[1025]; 93 int main(void) 94 { 95 int n, m; 96 while(~scanf("%d %d", &n, &m)) 97 { 98 init(); 99 memset(peo, 0, sizeof(peo)); 100 int S = (1 << m) + m + 1, T = S + 1; 101 for(int i = 1; i <= n; i++) 102 { 103 int tmp = 0; 104 for(int j = 0; j < m; j++) 105 { 106 int x; 107 scanf("%d", &x); 108 tmp += x << j; 109 } 110 peo[tmp]++; 111 } 112 for(int i = 1; i < (1 << m); i++) 113 { 114 if(!peo[i]) continue; 115 ad(S, i, peo[i]); 116 for(int j = 0; j < m; j++) 117 if(i & (1 << j)) ad(i, (1 << m) + j, INF); 118 } 119 for(int i = 0; i < m; i++) 120 { 121 int x; 122 scanf("%d", &x); 123 ad((1 << m) + i, T, x); 124 } 125 puts(Dinic(S, T) == n ? "YES" : "NO"); 126 } 127 return 0; 128 }
2.22
HDU 3081 Marriage Match II
还要二分一下。
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <algorithm> 5 #include <queue> 6 using namespace std; 7 const int INF = 1e9; 8 const int maxn = 2e5 + 10; 9 int lv[maxn], it[maxn]; 10 int cnt, h[maxn]; 11 12 struct edge 13 { 14 int to, pre, cap; 15 } e[maxn<<1]; 16 17 void init() 18 { 19 memset(h, -1, sizeof(h)); 20 cnt = 0; 21 } 22 23 void add(int from, int to, int cap) 24 { 25 e[cnt].pre = h[from]; 26 e[cnt].to = to; 27 e[cnt].cap = cap; 28 h[from] = cnt; 29 cnt++; 30 } 31 32 void ad(int from, int to, int cap) 33 { 34 add(from, to, cap); 35 add(to, from, 0); 36 } 37 38 void bfs(int s) 39 { 40 memset(lv, -1, sizeof(lv)); 41 queue<int> q; 42 lv[s] = 0; 43 q.push(s); 44 while(!q.empty()) 45 { 46 int v = q.front(); q.pop(); 47 for(int i = h[v]; i >= 0; i = e[i].pre) 48 { 49 int cap = e[i].cap, to = e[i].to; 50 if(cap > 0 && lv[to] < 0) 51 { 52 lv[to] = lv[v] + 1; 53 q.push(to); 54 } 55 } 56 } 57 } 58 59 int dfs(int v, int t, int f) 60 { 61 if(v == t) return f; 62 for(int &i = it[v]; i >= 0; i = e[i].pre) 63 { 64 int &cap = e[i].cap, to = e[i].to; 65 if(cap > 0 && lv[v] < lv[to]) 66 { 67 int d = dfs(to, t, min(f, cap)); 68 if(d > 0) 69 { 70 cap -= d; 71 e[i^1].cap += d; 72 return d; 73 } 74 } 75 } 76 return 0; 77 } 78 79 int Dinic(int s, int t) 80 { 81 int flow = 0; 82 while(1) 83 { 84 bfs(s); 85 if(lv[t] < 0) return flow; 86 memcpy(it, h, sizeof(it)); 87 int f; 88 while((f = dfs(s, t, INF)) > 0) flow += f; 89 } 90 } 91 92 int fa[111], r[111]; 93 int Find(int x) 94 { 95 return fa[x] == x ? x : fa[x] = Find(fa[x]); 96 } 97 98 void Union(int x, int y) 99 { 100 x = Find(x); 101 y = Find(y); 102 if(x != y) 103 { 104 if(r[x] < r[y]) swap(x, y); 105 fa[y] = x; 106 r[x] += r[y]; 107 } 108 } 109 110 int G[111][111]; 111 int main(void) 112 { 113 int T; 114 scanf("%d", &T); 115 while(T--) 116 { 117 int n, m, f; 118 scanf("%d %d %d", &n, &m, &f); 119 memset(G, 0, sizeof(G)); 120 for(int i = 0; i <= n; i++) fa[i] = i, r[i] = 1; 121 for(int i = 0; i < m; i++) 122 { 123 int u, v; 124 scanf("%d %d", &u, &v); 125 G[u][v] = 1; 126 } 127 for(int i = 0; i < f; i++) 128 { 129 int u, v; 130 scanf("%d %d", &u, &v); 131 Union(u, v); 132 } 133 int S = n + n + 1, T = S + 1; 134 for(int i = 1; i <= n; i++) 135 { 136 int f = Find(i); 137 if(f == i) continue; 138 for(int j = 1; j <= n; j++) G[f][j] |= G[i][j]; 139 } 140 int L = 0, R = n, mid; 141 while(L < R) 142 { 143 mid = R - (R - L) / 2; 144 init(); 145 for(int i = 1; i <= n; i++) ad(n + i, T, mid); 146 for(int i = 1; i <= n; i++) 147 { 148 if(Find(i) != i) continue; 149 ad(S, i, r[i] * mid); 150 for(int j = 1; j <= n; j++) 151 if(G[i][j]) ad(i, n + j, r[i]); 152 } 153 if(Dinic(S,T) != mid * n) R = mid - 1; 154 else L = mid; 155 } 156 printf("%d ", L); 157 } 158 return 0; 159 }
2.23
TC SRM 682 Div1 300 SmilesTheFriendshipUnicorn
暴力就好了。
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <vector> 5 using namespace std; 6 const int maxn = 2e5 + 10; 7 int ok, cnt, h[2020], vis[2020]; 8 9 struct edge 10 { 11 int to, pre; 12 } e[maxn<<1]; 13 14 void add(int from, int to) 15 { 16 cnt++; 17 e[cnt].pre = h[from]; 18 e[cnt].to = to; 19 h[from] = cnt; 20 } 21 22 void init() 23 { 24 cnt = 0; 25 memset(h, 0, sizeof(h)); 26 } 27 28 void DFS(int x, int d) 29 { 30 vis[x] = 1; 31 if(d == 5) {ok = 1; return;} 32 for(int i = h[x]; i; i = e[i].pre) 33 { 34 int to = e[i].to; 35 if(vis[to]) continue; 36 DFS(to, d + 1); 37 } 38 vis[x] = 0; 39 return; 40 } 41 42 class SmilesTheFriendshipUnicorn 43 { 44 45 public: 46 47 string hasFriendshipChain(int N, vector <int> A, vector <int> B) 48 { 49 init(); 50 int m = A.size(); 51 for(int i = 0; i < m; i++) 52 { 53 add(A[i], B[i]); 54 add(B[i], A[i]); 55 } 56 for(int i = 0; i < N; i++) 57 { 58 ok = 0; 59 memset(vis, 0, sizeof(vis)); 60 DFS(i, 1); 61 if(ok) return string("Yay!"); 62 } 63 return string(":("); 64 } 65 66 };
TC SRM 682 Div1 450 SuccessfulMerger
判环判成sb也是没誰了。
#include <iostream> #include <cstdio> #include <cstring> #include <vector> using namespace std; const int maxn = 2e5 + 10; int cnt, h[55]; int sz[55], leaf[55]; int fa[55], is[55], vis[55]; struct edge { int to, pre; } e[maxn<<1]; void add(int from, int to) { cnt++; e[cnt].pre = h[from]; e[cnt].to = to; h[from] = cnt; } void init() { cnt = 0; memset(h, 0, sizeof(h)); memset(is, 0, sizeof(is)); memset(fa, -1, sizeof(fa)); memset(vis, 0, sizeof(vis)); } void DFS(int x, int f) { vis[x] = 2; if(fa[x] != -1) { int p = f; while(p != x) { is[p] = 1; p = fa[p]; } is[x] = is[f] = 1; return; } fa[x] = f; for(int i = h[x]; i; i = e[i].pre) { int to = e[i].to; if(to == f || vis[to] == 1) continue; DFS(to, x); } vis[x] = 1; } void DFS2(int x, int f) { sz[x] = 1; int tot = 0; for(int i = h[x]; i; i = e[i].pre) { int to = e[i].to; if(to == f || is[to]) continue; tot++; DFS2(to, x); sz[x] += sz[to]; leaf[x] += leaf[to]; } if(tot == 0) leaf[x] = 1; return; } class SuccessfulMerger { public: int minimumMergers(vector <int> road) { init(); int N = road.size(), two = 0; for(int i = 0; i < N; i++) { add(i, road[i]); add(road[i], i); if(i == road[road[i]]) { two = 1; is[i] = is[road[i]] = 1; } } if(!two) DFS(0, -2); int ans = 0, r = 0, one = 0; for(int i = 0; i < N; i++) { if(!is[i]) continue; r++; DFS2(i, -1); if(sz[i] == 1) one = 1; else ans += sz[i] - leaf[i] - 1; } return ans + r - 1 - one; } };
HDU 3416 Marriage Match IV
SPFA跑跑Dinic跑跑。
#include <iostream> #include <cstdio> #include <cstring> #include <algorithm> #include <queue> using namespace std; const int maxn = 2e5 + 10; const int INF = 1e9; int lv[1111], it[1111]; int dist[1111], vis[1111]; int cnt, h[1111]; struct edge { int to, pre, cap; } e[maxn<<1]; void init() { memset(h, -1, sizeof(h)); cnt = 0; } void add(int from, int to, int cap) { e[cnt].pre = h[from]; e[cnt].to = to; e[cnt].cap = cap; h[from] = cnt; cnt++; } void ad(int from, int to, int cap) { add(from, to, cap); add(to, from, 0); } vector<int> ve[1111]; void SPFA(int s) { memset(vis, 0, sizeof(vis)); for(int i = 0; i < 1111; i++) dist[i] = INF; dist[s] = 0; queue<int> q; q.push(s); while(!q.empty()) { int v = q.front(); q.pop(); vis[v] = 0; for(int i = h[v]; i >= 0; i = e[i].pre) { int to = e[i].to, cost = e[i].cap; if(dist[to] > dist[v] + cost) { ve[to].clear(); ve[to].push_back(v); dist[to] = dist[v] + cost; if(!vis[to]) q.push(to); vis[to] = 1; } else if(dist[to] == dist[v] + cost) { ve[to].push_back(v); if(!vis[to]) q.push(to); vis[to] = 1; } } } } void bfs(int s) { memset(lv, -1, sizeof(lv)); queue<int> q; lv[s] = 0; q.push(s); while(!q.empty()) { int v = q.front(); q.pop(); for(int i = h[v]; i >= 0; i = e[i].pre) { int cap = e[i].cap, to = e[i].to; if(cap > 0 && lv[to] < 0) { lv[to] = lv[v] + 1; q.push(to); } } } } int dfs(int v, int t, int f) { if(v == t) return f; for(int &i = it[v]; i >= 0; i = e[i].pre) { int &cap = e[i].cap, to = e[i].to; if(cap > 0 && lv[v] < lv[to]) { int d = dfs(to, t, min(f, cap)); if(d > 0) { cap -= d; e[i^1].cap += d; return d; } } } return 0; } int Dinic(int s, int t) { int flow = 0; while(1) { bfs(s); if(lv[t] < 0) return flow; memcpy(it, h, sizeof(it)); int f; while((f = dfs(s, t, INF)) > 0) flow += f; } } int main(void) { int t; scanf("%d", &t); while(t--) { init(); int n, m; scanf("%d %d", &n, &m); for(int i = 0; i < m; i++) { int a, b, c; scanf("%d %d %d", &a, &b, &c); add(a, b, c); } int S, T; scanf("%d %d", &S, &T); SPFA(S); init(); queue<int> q; q.push(T); memset(vis, 0, sizeof(vis)); while(!q.empty()) { int v = q.front(); q.pop(); int sz = ve[v].size(); for(int i = 0; i < sz; i++) { int u = ve[v][i]; ad(u, v, 1); if(vis[u]) continue; q.push(u); vis[u] = 1; } } printf("%d ", Dinic(S, T)); } return 0; }
2.24-2.27
什么都没干。