【bzoj4806~bzoj4809】 象棋四连发 DP-高精度-匈牙利算法-dfs

都是经典题了吧。。我好无聊。。

4806

4806-1801是双倍经验。。DP方程看代码吧。。

 /* http://www.cnblogs.com/karl07/ */
 #include <cstdlib>
 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <algorithm>
 using namespace std;

 #define ll long long
 //#define P 9999973 //bzoj1801
 #define P 999983 //bzoj4806
 #define C(x) ((x)*(x-1)/2)
 int n,m;
 ll f[][][];

 int main(){
     scanf("%d%d",&n,&m);
     f[][][]=;
     for (int i=;i<=n;i++){
         for (int j=;j<=m;j++){
             for (int k=;k<=m-j;k++){
                 f[i][j][k]+=f[i-][j][k];
                 if (j>=)          f[i][j][k]+=f[i-][j-][k]*(m-j-k+);
                 if (k>= && j<=m-)f[i][j][k]+=f[i-][j+][k-]*(j+);
                 if (j>=)          f[i][j][k]+=f[i-][j-][k]*C(m-j-k+);
                 if (k>= && j<=m-)f[i][j][k]+=f[i-][j+][k-]*C(j+);
                 if (j>= && k>=)  f[i][j][k]+=f[i-][j][k-]*j*(m-j-k+);
                 f[i][j][k]%=P;
             }
         }
     }
     ll ans=;
     for (int i=;i<=m;i++){
         for (int j=;j<=m-i;j++){
             ans+=f[n][i][j];
             ans%=P;
         }
     }
     printf("%lld\n",ans);
     return ;
 }

炮

4807

就是 max(m,n) C min (m,n)

 /* http://www.cnblogs.com/karl07/ */
 #include <cstdlib>
 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <algorithm>
 using namespace std;
 struct INT {
     int b,a[];
     INT (){b=; for (int i=;i<=;i++) a[i]=;}
 };
 int A,B,c,n,m;
 int P[],p[],cnt[],ip[];
 INT Int(int x){
     INT a;
     for (a.b= ; x ; a.a[++a.b]=x%,x/=);
     return a;
 }

 INT operator * (const INT &x,const INT &y){
     INT a;
     a.b=min(,x.b+y.b-);
     for (int i=;i<=x.b;i++) for (int j=;j<=y.b;j++) if (i+j-<=) a.a[i+j-]+=x.a[i]*y.a[j];
     for (int i=;i<=a.b;a.b+=(i==a.b && a.a[i+] && i+<=),i++)  a.a[i+]+=a.a[i]/,a.a[i]%=;
     for (;a.a[a.b]== && a.b!=; a.b--);
     return a;
 }

 void print_INT(INT x){
     for (int i=min(x.b,);i>=;i--) printf("%d",x.a[i]);
     puts("");
 }

 void Prime(int n){
     for (int i=;i<=n;i++){
         if (!P[i]){
             p[++c]=i,ip[i]=c;
             for (int j=i+i;j<=n;j+=i) P[j]=;
         }
     }
 }

 void pt(int x) {
     printf("%d\n",x);
 }

 void fac(int x,int y){
     for (int i=;i<=c && P[x];i++) while (!(x%p[i])) x/=p[i],cnt[i]+=y;
     cnt[ip[x]]+=y;
 }

 INT ans=Int();
 int main(){
     scanf("%d%d",&A,&B);
     n=max(A,B),m=max(max(A,B)-min(A,B),min(A,B));
     Prime(n);
     for (int i=m+;i<=n;i++) fac(i,);
     for (int i=;i<=n-m;i++) fac(i,-);
     for (int i=;i<=c;i++) while (cnt[i]--) ans=ans*Int(p[i]);
     print_INT(ans);
     return ;
 }

车

4808

黑白染色然后匈牙利

 /* http://www.cnblogs.com/karl07/ */
 #include <cstdlib>
 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <algorithm>
 using namespace std;

 struct edge{
     int next,to;
 }e[];
 int ade,n,m,cnt,T,c;
 int x[]={,,-,-,-,,,-};
 int y[]={,,-,-,,-,-,};
 int mp[][],id[][],first[],vis[],match[];

 void addedge(int x,int y){
     e[++ade].next=first[x];
     e[ade].to=y;
     first[x]=ade;
 }

 bool check(int x,int y){
     return (x>= && x<=n && y>= && y<=m && !mp[x][y]);
 }

 #define s e[x].to
 bool hungary(int p){
     for (int x=first[p];x;x=e[x].next){
         if (vis[s]!=T){
             vis[s]=T;
             if (!match[s] || hungary(match[s])) {match[s]=p; return ;}
         }
     }
     return ;
 }
 #undef s

 int main(){
     scanf("%d%d",&n,&m);
     for (int i=;i<=n;i++){
         for (int j=;j<=m;j++){
             scanf("%d",&mp[i][j]);
             cnt+=(!mp[i][j]);
             id[i][j]=++c;
         }
     }
     for (int i=;i<=n;i++)
         for (int j=;j<=m;j++)
             if (((i+j)&) && !mp[i][j])for (int k=;k<;k++) if (check(i+x[k],j+y[k])) addedge(id[i][j],id[i+x[k]][j+y[k]]);
     for (int i=;i<=n;i++){
         for (int j=;j<=m;j++){
             if (!mp[i][j] && ((i+j)&)){
                 T=id[i][j];
                 cnt-=hungary(T);
             }
         }
     }
     printf("%d\n",cnt);
     return ;
 }

马

4809

直接dfs

 /* http://www.cnblogs.com/karl07/ */
 #include <cstdlib>
 #include <cstdio>
 #include <cstring>
 #include <cmath>
 #include <algorithm>
 using namespace std;

 int n,ans;
 int ban[][],y[],a[],b[];

 void dfs(int i){
     if (i>n) {ans++; return;}
     for(int j=;j<=n;j++) if (!(ban[i][j] || y[j] || a[i+j-] || b[n-i+j] )){
         y[j]=a[i+j-]=b[n-i+j]=;
         dfs(i+);
         y[j]=a[i+j-]=b[n-i+j]=;
     }
 }

 int main(){
     scanf("%d",&n);
     for (int i=;i<=n;i++) for (int j=;j<=n;j++) scanf("%d",&ban[i][j]);
     dfs();
     printf("%d\n",ans);
     return ;
 }

皇后