官方解题报告http://blog.sina.com.cn/s/blog_a19ad7a10102uyxr.html
Matrix multiplication http://acm.hdu.edu.cn/showproblem.php?pid=4920
1 #include<cstdio> 2 #include<cctype> 3 const int M=810; 4 int a[M][M],b[M][M],c[M][M]; 5 inline int getint(){ 6 int res=0; 7 char tmp; 8 while(!isdigit(tmp=getchar())); 9 do{ 10 res=(res<<3)+(res<<1)+tmp-'0'; 11 }while(isdigit(tmp=getchar())); 12 return res; 13 } 14 int main(){ 15 int n,x,i,j,k; 16 while(~scanf("%d",&n)){ 17 for(i=0;i<n;i++){ 18 for(j=0;j<n;j++){ 19 a[i][j]=getint(); 20 a[i][j]%=3; 21 } 22 } 23 for(i=0;i<n;i++){ 24 for(j=0;j<n;j++){ 25 b[i][j]=getint(); 26 b[i][j]%=3; 27 c[i][j]=0; 28 } 29 } 30 for(k=0;k<n;k++){ 31 for(i=0;i<n;i++){ 32 if(a[i][k]){ 33 for(j=0;j<n;j++){ 34 c[i][j]+=a[i][k]*b[k][j]; 35 } 36 } 37 } 38 } 39 for(i=0;i<n;i++){ 40 for(j=0;j<n;j++){ 41 if(j) putchar(' '); 42 putchar(c[i][j]%3+'0'); 43 } 44 putchar(' '); 45 } 46 } 47 return 0; 48 }
Inversion http://acm.hdu.edu.cn/showproblem.php?pid=4911
1 #include<cstdio> 2 #include<cstring> 3 #include<cctype> 4 typedef __int64 LL; 5 const int M=100010; 6 int a[M]; 7 class InverseNum { //逆序对数O(nlogn) 8 #define _cp(a,b) ((a)<=(b)) //可更改元素类型和比较函数 9 typedef int typev; 10 typev b[M]; 11 public: 12 LL inv(int n,typev a[]) { //传入序列长度和内容,返回逆序对数 13 int l=n>>1,r=n-l,i,j; 14 LL ret=(r>1?(inv(l,a)+inv(r,a+l)):0); 15 for (i=j=0; i<=l; b[i+j]=a[i],i++) 16 for (ret+=j; j<r&&(i==l||!_cp(a[i],a[l+j])); b[i+j]=a[l+j],j++); 17 memcpy(a,b,sizeof(typev)*n); 18 return ret; 19 } 20 } gx; 21 int getint(){ 22 int res=0; 23 char tmp; 24 while(!isdigit(tmp=getchar())); 25 do{ 26 res=(res<<3)+(res<<1)+tmp-'0'; 27 }while(isdigit(tmp=getchar())); 28 return res; 29 } 30 int main(){ 31 int n,k; 32 while(~scanf("%d%d",&n,&k)){ 33 for(int i=0;i<n;i++){ 34 // scanf("%d",&a[i]); 35 a[i]=getint(); 36 } 37 LL ans=gx.inv(n,a); 38 if(ans<k) ans=0; 39 else ans-=k; 40 printf("%I64d ",ans); 41 } 42 return 0; 43 }
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