【题目链接】
300题了orz。
【POPOQQQ的题解】%%%神奇的建图。
/* Pigonometry */ #include <cstdio> #include <cstring> #include <algorithm> using namespace std; const int maxn = 305, maxm = 10005, maxq = 10000, inf = 0x3f3f3f3f; int n, head[maxn], cnt, depth[maxn], bg, ed, way[maxn], q[maxq]; bool vis[maxn]; struct _edge { int v, w, c, next; } g[maxm << 1]; inline int iread() { int f = 1, x = 0; char ch = getchar(); for(; ch < '0' || ch > '9'; ch = getchar()) f = ch == '-' ? -1 : 1; for(; ch >= '0' && ch <= '9'; ch = getchar()) x = x * 10 + ch - '0'; return f * x; } inline void add(int u, int v, int w, int c) { g[cnt] = (_edge){v, w, c, head[u]}; head[u] = cnt++; } inline void insert(int u, int v, int w, int c) { add(u, v, w, c); add(v, u, 0, -c); } inline bool spfa() { for(int i = 0; i <= ed; i++) depth[i] = inf; int h = 0, t = 0, u, i; depth[q[t++] = bg] = 0; while(h != t) for(i = head[u = q[h++]], vis[u] = 0; ~i; i = g[i].next) if(g[i].w && depth[g[i].v] > depth[u] + g[i].c) { depth[g[i].v] = depth[u] + g[i].c; way[g[i].v] = i; if(!vis[g[i].v]) vis[q[t++] = g[i].v] = 1; } return depth[ed] != inf; } inline int back() { int flow = inf, res = 0; for(int u = ed; u != bg; u = g[way[u] ^ 1].v) flow = min(flow, g[way[u]].w); for(int u = ed; u != bg; u = g[way[u] ^ 1].v) g[way[u]].w -= flow, g[way[u] ^ 1].w += flow, res += g[way[u]].c * flow; return res; } int main() { n = iread(); bg = 0; ed = n + 1; for(int i = 0; i <= ed; i++) head[i] = -1; cnt = 0; for(int i = 1; i <= n; i++) { int x = iread(); insert(i, ed, x, 0); while(x--) { int v = iread(), w = iread(); insert(i, v, inf, w); insert(bg, v, 1, w); } if(i != 1) insert(i, 1, inf, 0); } int ans = 0; while(spfa()) ans += back(); printf("%d\n", ans); return 0; }