URAL 1028. Stars

problem url: http://acm.timus.ru/problem.aspx?space=1&num=1028

Got two methods here. One uses hash table which will give you O(Nsqrt(N)) , another uses segment tree(binary search..) which gives you O(Nlog(N))

**hash table approach:


#include <cstdio>


#include <cstddef>


#include <iostream>


#include <math.h>




#define MAX_XY 32000


#define MAX_COUNT 15000




using namespace std;




void main()




...{


int count = 0;


int i=0;


int sx,sy;




int bSize =0 ; //bucket size


int bNum = 0; //total bucket number






int p[MAX_XY+1] = ...{0};




int* lList = NULL;


int *b = NULL;




scanf("%d", &count);




bSize = (int)sqrt((double)MAX_XY);


bNum = (MAX_XY+1) / bSize + 1;




b = (int*)malloc(sizeof(int)*bNum);


memset(b, 0, sizeof(int)*bNum);




lList = (int*)malloc(sizeof(int) * count);


memset(lList, 0, sizeof(int)*count);




for(i =0;i<count;++i)




...{


int bCur = 0;//current bucket index


int lCur = 0;//current level




scanf("%d %d", &sx, &sy);




bCur = sx / bSize;






/**/////calculate level


int j = 0;




for(j =0; j<bCur;++j)




...{


lCur += b[j];


}




for(j= bSize*bCur; j<=sx; ++j)




...{


lCur += p[j];


}




lList[lCur]++;




/**////////////////////




b[bCur]++;


p[sx]++;


}




//print out result


for(i=0;i<count;++i)




...{


printf("%d ",lList[i]);


}




free(b);


free(lList);


}

**segment tree approach:


#include <cstdio>


#include <cstddef>


#include <iostream>


#include <math.h>




#define MAX_XY 32000


#define MAX_COUNT 15000






int vals[MAX_XY *4 +1] = ...{0};


int lList[MAX_COUNT];




using namespace std;




void insertstar(int p, int b, int e, int x)




...{


int m = (b+e) >> 1;




if(e != b)




...{


if(x <= m)




...{


insertstar(p<<1, b, m, x);




}else




...{


insertstar((p<<1)+1, m+1, e, x);


}


}


vals[p] ++;


}




int getlevel(int p, int b, int e, int x)




...{


int m = (b+e) >> 1;




if( e == b)




...{


return vals[p];


}


else




...{


if( x == e)




...{


return vals[p];


}


else if(x > m)




...{


return getlevel(p<<1, b, m, m) + getlevel((p<<1)+1,m+1, e, x);


}else




...{


return getlevel(p<<1, b, m, x);


}


}


}




void main()




...{


int count = 0;


int i=0;


int sx,sy;




//get star number


//cin>>count;


scanf("%d", &count);




memset(lList, 0, sizeof(int)*MAX_COUNT);




for(i =0;i<count;++i)




...{


int lCur = 0;//current level




//cin>>sx>>sy;


scanf("%d %d", &sx, &sy);




//get level


lCur = getlevel(1, 0, MAX_XY, sx);




lList[lCur]++;




insertstar(1,0,MAX_XY,sx);




/**////////////////////


}




for(i=0;i<count;++i)




...{


printf("%d ",lList[i]);


}


}