Recently i solved a interesting problem. You have to find number of quadrat submatrix length of K, and number of distinct values of submatrix must be <= q. You have to solve this problem for each k from 1 to n. q <= 10, n <= 1500. After some thought, i understood that i can not solve this problem for q <= 1500. May you give some hints or solution for constant k. Shortly, i want to be able to find number of distinct values in submatrix. Thanks!