struct Graph { int n, match[maxn]; bool adj[maxn][maxn]; void clear() { memset(adj, 0, sizeof(adj)); n =0; } void insert(constint&u, constint&v) { get_max(n, max(u, v) +1); adj[u][v] = adj[v][u] =1; } int max_match() { memset(match, -1, sizeof(match)); int ans =0; for (int i =0; i < n; ++i) { if (match[i] ==-1) { ans += bfs(i); } } return ans; } int Q[maxn], pre[maxn], base[maxn]; bool hash[maxn]; bool in_blossom[maxn]; int bfs(int p) { memset(pre, -1, sizeof(pre)); memset(hash, 0, sizeof(hash)); for (int i =0; i < n; ++i) { base[i] = i; } Q[0] = p; hash[p] =1; for (int s =0, t =1; s < t; ++s) { int u = Q[s]; for (int v =0; v < n; ++v) { if (adj[u][v] &&base[u] !=base[v] && v != match[u]) { if (v == p || (match[v] !=-1&& pre[match[v]] !=-1)) { int b = contract(u, v); for (int i =0; i < n; ++i) { if (in_blossom[base[i]]) { base[i] = b; if (hash[i] ==0) { hash[i] =1; Q[t++] = i; } } } }elseif (pre[v] ==-1) { pre[v] = u; if (match[v] ==-1) { argument(v); return1; }else{ Q[t++] = match[v]; hash[match[v]] =1; } } } } } return0; } void argument(int u) { while (u !=-1) { int v = pre[u]; int k = match[v]; match[u] = v; match[v] = u; u = k; } } void change_blossom(int b, int u) { while (base[u] != b) { int v = match[u]; in_blossom[base[v]] = in_blossom[base[u]] =true; u = pre[v]; if (base[u] != b) { pre[u] = v; } } } int contract(int u, int v) { memset(in_blossom, 0, sizeof(in_blossom)); int b = find_base(base[u], base[v]); change_blossom(b, u); change_blossom(b, v); if (base[u] != b) { pre[u] = v; } if (base[v] != b) { pre[v] = u; } return b; } int find_base(int u, int v) { bool in_path[maxn] ={}; while (true) { in_path[u] =true; if (match[u] ==-1) { break; } u =base[pre[match[u]]]; } while (!in_path[v]) { v =base[pre[match[v]]]; } return v; } };