[POJ3041] Asteroids (minimum point overlay-Hungarian algorithm)

Portal

Test instructions: To a n*n matrix, some lattice have obstacles, ask us to eliminate these obstacles, asked each time to eliminate a row or a column of obstacles, at least a few times. Analytical:

Take each row and each column as a point on either side of the two-part graph.

If a lattice has a barrier, it corresponds to the row and column edge.

Select the fewest points so that all edges are overwritten.

Minimum point overlay.

--code

1#include <cstdio>2#include <cstring>3 #defineM (x, a) memset (a, X, sizeof (a))4 5 using namespacestd;6 7 Const intMAXN =501;8 intN, K, CNT, ans;9 intHEAD[MAXN], NEXT[MAXN * MAXN], TO[MAXN *MAXN], BELONG[MAXN];Ten BOOLVIS[MAXN]; One  AInlinevoidAddintXinty) - { -TO[CNT] =y; theNEXT[CNT] =Head[x]; -HEAD[X] = cnt++; - } -  +InlineBOOLFindintu) - { +     intI, V; A      for(i = head[u]; I! =-1; i =Next[i]) at     { -v =To[i]; -         if(!Vis[v]) -         { -VIS[V] =1; -             if(!belong[v] | |find (Belong[v])) in             { -BELONG[V] =u; to                 return 1; +             } -         } the     } *     return 0; $ }Panax Notoginseng  - intMain () the { +     intI, x, y; Ascanf"%d%d", &n, &k); theM (-1, head); +      for(i =1; I <= K; i++) -     { $scanf"%d%d", &x, &y); $ Add (x, y); -     } -      for(i =1; I <= N; i++) the     { -M0, Vis);Wuyi         if(Find (i)) ans++; the     } -printf"%d", ans); Wu     return 0; -}

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[POJ3041] Asteroids (minimum point overlay-Hungarian algorithm)