POJ 3670 Intervals (billing flow)

POJ 3680 Intervals

Question link

Question: given some intervals, each interval has a weight value, which is required to be overwritten. Each vertex can cover up to k times and ask how many weights can be obtained at most.

Train of Thought: Typical range k coverage problem, range edge capacity 1, cost-w, then other points adjacent to the two sides of the edge, capacity k, cost 0, just run the charge flow

Code:

# Include <cstdio> # include <cstring> # include <vector> # include <queue> # include <algorithm> using namespace std; const int MAXNODE = 100005; const int MAXEDGE = 2005; typedef int Type; const Type INF = 0x3f3f3f; struct Edge {int u, v; Type cap, flow, cost; Edge () {} Edge (int u, int v, Type cap, Type flow, Type cost) {this-> u = u; this-> v = v; this-> cap = cap; this-> flow = flow; this-> cost = cost ;}}; struct MCFC { Int n, m, s, t; Edge edges [MAXEDGE]; int first [MAXNODE]; int next [MAXEDGE]; int inq [MAXNODE]; Type d [MAXNODE]; int p [MAXNODE]; Type a [MAXNODE]; void init (int n) {this-> n = n; memset (first,-1, sizeof (first )); m = 0;} void add_Edge (int u, int v, Type cap, Type cost) {edges [m] = Edge (u, v, cap, 0, cost ); next [m] = first [u]; first [u] = m ++; edges [m] = Edge (v, u, 0, 0,-cost ); next [m] = first [v]; first [v] = m ++;} bool Bellmanford (int s, int t, Type & flow, Type & cost) {for (int I = 0; I <n; I ++) d [I] = INF; memset (inq, false, sizeof (inq); d [s] = 0; inq [s] = true; p [s] = s; a [s] = INF; queue <int> Q; Q. push (s); while (! Q. empty () {int u = Q. front (); Q. pop (); inq [u] = false; for (int I = first [u]; I! =-1; I = next [I]) {Edge & e = edges [I]; if (e. cap> e. flow & d [e. v]> d [u] + e. cost) {d [e. v] = d [u] + e. cost; p [e. v] = I; a [e. v] = min (a [u], e. cap-e. flow); if (! Inq [e. v]) {Q. push (e. v); inq [e. v] = true ;}}}if (d [t] = INF) return false; flow + = a [t]; cost + = d [t] * a [t]; int u = t; while (u! = S) {edges [p [u]. flow + = a [t]; edges [p [u] ^ 1]. flow-= a [t]; u = edges [p [u]. u;} return true;} Type Mincost (int s, int t) {Type flow = 0, cost = 0; while (bellmanford (s, t, flow, cost )); return cost ;}} gao; const int N = 405; int t, n, k, save [N], sn; int main () {scanf ("% d ", & t); while (t --) {scanf ("% d", & n, & k); int l, r, w; sn = 0; gao. init (100005); while (n --) {scanf ("% d", & l, & r, & w ); save [sn ++] = l; save [sn ++] = r; gao. add_Edge (l, r, 1,-w);} save [sn ++] = 0; save [sn ++] = 100001; sort (save, save + sn ); for (int I = 1; I <sn; I ++) gao. add_Edge (save [I-1], save [I], k, 0); printf ("% d \ n",-gao. mincost (0, 100001);} return 0 ;}

POJ 3670 Intervals (billing flow)