[Wikioi] 1922 server guard coexistence problem (network stream/Bipartite Graph Matching)

 

 

It's a battle in Hungary. Hello? And network stream are not all N ^ 3 .... (Update: What !!!!!! A silent problem was found ,.!!!! The structure is faster than the array. orz, the rhythm is wrong .... In the future, we will write the structural rhythm in all the diagrams...

#include <cstdio>#include <cstring>#include <cmath>#include <string>#include <iostream>#include <algorithm>using namespace std;#define rep(i, n) for(int i=0; i<(n); ++i)#define for1(i,a,n) for(int i=(a);i<=(n);++i)#define for2(i,a,n) for(int i=(a);i<(n);++i)#define for3(i,a,n) for(int i=(a);i>=(n);--i)#define for4(i,a,n) for(int i=(a);i>(n);--i)#define CC(i,a) memset(i,a,sizeof(i))#define max(a,b) ((a)>(b)?(a):(b))#define min(a,b) ((a)<(b)?(a):(b))#define read(a) scanf("%d", &a)#define print(a) printf("%d", a)#define num(i, j) ((i-1)*n+j)#define who(i, j) (i%2==j%2)#define arr(a, n) for1(i, 1, n) { for1(j, 1, n) print(a[i][j]); printf("\n"); }#define arr2(a, n) for1(i, 1, n) print(a[i]); printf("\n")inline int getnum() { int ret=0; char c; int k=1; for(c=getchar(); c<‘0‘ || c>‘9‘; c=getchar()) if(c==‘-‘) k=-1; for(; c>=‘0‘ && c<=‘9‘; c=getchar()) ret=ret*10+c-‘0‘; return k*ret; }const int fx[8]={1, 1, 2, 2, -1, -1, -2, -2}, fy[8]={-2, 2, -1, 1, -2, 2, -1, 1};const int N=205*205, M=N*8+100;int ihead[N], inext[M], to[M], cnt, x[N], cont, ly[N], n, m, mm[205][205];bool vis[N];inline void add(const int &u, const int &v) {inext[++cnt]=ihead[u]; ihead[u]=cnt; to[cnt]=v;}bool ifind(const int &x) {vis[x]=true;for(int i=ihead[x]; i; i=inext[i]) if(!vis[to[i]]) {vis[to[i]]=true;if(!ly[to[i]] || ifind(ly[to[i]])) {ly[to[i]]=x;return true;}}return false;}int main() {read(n); read(m);int a, b, nx, ny, ans=0;rep(i, m) read(a), read(b), mm[a][b]=1;for1(i, 1, n) for1(j, 1, n) if(!mm[i][j] && who(i, j)) {rep(k, 8) {nx=i+fx[k], ny=j+fy[k];if(mm[nx][ny] || nx<1 || nx>n || ny<1 || ny>n) continue;add(num(i, j), num(nx, ny));}x[++cont]=num(i, j);}for1(i, 1, cont) {CC(vis, 0);if(ifind(x[i])) ans++;}print(n*n-ans-m);return 0;}

 

Stopped, and only the code network flow is allowed.

TLE's numerous AC orz (same as above, array and structure problems...

#include <cstdio>#include <cstring>#include <cmath>#include <string>#include <iostream>#include <algorithm>using namespace std;#define rep(i, n) for(int i=0; i<(n); ++i)#define for1(i,a,n) for(int i=(a);i<=(n);++i)#define for2(i,a,n) for(int i=(a);i<(n);++i)#define for3(i,a,n) for(int i=(a);i>=(n);--i)#define for4(i,a,n) for(int i=(a);i>(n);--i)#define CC(i,a) memset(i,a,sizeof(i))#define max(a,b) ((a)>(b)?(a):(b))#define min(a,b) ((a)<(b)?(a):(b))#define read(a) a=getnum()#define print(a) printf("%d", a)#define num(i, j) ((i-1)*n+j)#define who(i, j) (!((i+j)%2))#define arr(a, n) for1(i, 1, n) { for1(j, 1, n) print(a[i][j]); printf("\n"); }#define arr2(a, n) for1(i, 1, n) print(a[i]); printf("\n")inline int getnum() { int ret=0; char c; int k=1; for(c=getchar(); c<‘0‘ || c>‘9‘; c=getchar()) if(c==‘-‘) k=-1; for(; c>=‘0‘ && c<=‘9‘; c=getchar()) ret=ret*10+c-‘0‘; return k*ret; }const int fx[8]={1, 1, 2, 2, -1, -1, -2, -2}, fy[8]={2, -2, 1, -1, 2, -2, 1, -1};const int N=205*205, M=500001, oo=~0u>>1;int ihead[N], cnt=1, n, m;int gap[N], p[N], d[N], cur[N];bool mm[205][205];struct dd { int to, from, cap, next; }e[M];inline void add(const int &u, const int &v, const int &c) {e[++cnt].next=ihead[u]; ihead[u]=cnt; e[cnt].from=u; e[cnt].to=v; e[cnt].cap=c;e[++cnt].next=ihead[v]; ihead[v]=cnt; e[cnt].from=v; e[cnt].to=u; e[cnt].cap=0;}int isap(const int &s, const int &t, const int &n) {int flow=0, u=s, f, i, v;for1(i, 0, n) cur[i]=ihead[i];gap[0]=n;while(d[s]<n) {for(i=cur[u]; i; i=e[i].next) if(e[i].cap && d[u]==d[v=e[i].to]+1) break;if(i) {cur[u]=i; p[v]=i; u=v;if(u==t) {for(f=oo; u!=s; u=e[p[u]].from) f=min(f, e[p[u]].cap);for(u=t; u!=s; u=e[p[u]].from) e[p[u]].cap-=f, e[p[u]^1].cap+=f;flow+=f;}}else {if(!(--gap[d[u]])) break;d[u]=n;cur[u]=ihead[u];for(i=cur[u]; i; i=e[i].next) if(e[i].cap && d[u]>d[e[i].to]+1)d[u]=d[e[i].to]+1;++gap[d[u]]; if(u!=s) u=e[p[u]].from;}}return flow;}int main() {read(n); read(m);int a, b, nx, ny, s=0, t=n*n+5;rep(i, m) read(a), read(b), mm[a][b]=1;for1(i, 1, n) for1(j, 1, n) if(!mm[i][j]) {if(who(i, j)) {rep(k, 8) {nx=i+fx[k], ny=j+fy[k];if(mm[nx][ny] || nx<1 || nx>n || ny<1 || ny>n) continue;add(num(i, j), num(nx, ny), oo);}add(s, num(i, j), 1);}else add(num(i, j), t, 1);}print(n*n-isap(s, t, t+1)-m);return 0;}