http://acm.timus.ru/rating.aspx?space=1&num=1001&count=10
solution of the problem requires an array of 128 * 1024 elements
and an element of the array must store 13 digits, ie double, whose size is 8 bytes.
128 * 1024 * 8 = 1MB of memory
how to solve the problem using 730Kb or less?

execution time depends on at what time starts the test?
ie of server load?

Try to use the array of chars:)