如何在C中找到最大数为1的区域？

I have a 500x500 2D matrix which contains values either 0 or 1.Is there any way to find out the highly concentrated region which contains value 1 or lets say a region with maximum no of 1's.I tried traversing the whole 2D matrix with a smaller (50x50 size array) but its taking a very long time. Is there is any other way which is more efficient and takes lesser execution time.I have to do this in C programming.I have a 500x500 2D matrix which contains value