SPOJ K-th Number
here is the link of a problem,I wrote O(n log n + m log^3 n) solution,but I have wa16, here is my code.
please help to find my mistake,also I am interested log n and log^2 n solutions.
Any help will be appreciated very much :)
for O((n+m) log n) solution see here
could you explain your solution?
Sort the array keeping track of indexes so I have A[0] is the index of smallest number and A[n-1] is the index of biggest number
Now if I want K-th smallest number in range [l,r] the naive way is like the code
int tmp=0; for(int i=0;i<n;i++){ if(l<=A[i] && A[i]<=r)tmp++; if(tmp==k){ cout<<A[i]<<endl; //output the index break; } }
This has complexity O(n) for each operation
I use sqrt decompstion to make it faster
Can you please comment your code a bit so that it makes it easier to understand? I have no idea what your pre[][] array does and not able to understand it from the link that you've posted.
pre[i][j] means how many indexes between 1 and j exists in ith block
it is hard to understand idea from your code, but when you explain I got it,thanks,great idea ;)
for O((n+m) log n) solution see here
could you explain your solution?
Sort the array keeping track of indexes so I have A[0] is the index of smallest number and A[n-1] is the index of biggest number
Now if I want K-th smallest number in range [l,r] the naive way is like the code
This has complexity O(n) for each operation
I use sqrt decompstion to make it faster
Can you please comment your code a bit so that it makes it easier to understand? I have no idea what your pre[][] array does and not able to understand it from the link that you've posted.
pre[i][j] means how many indexes between 1 and j exists in ith block
it is hard to understand idea from your code, but when you explain I got it,thanks,great idea ;)