what is mean by non decreasing order
Non-decreasing means exactly that. It's not quite the same as increasing, since it does not tell you what to do with identical values. Consider the sequence 1, 2, 2, 3, 4. It's a non-decreasing sequence because the values are in order, yet do not strictly increase from value to value (ie, 2 is not greater than 2).ncreasing means that every element is greater than the one before it. Non-decreasing means that no element is less than the element before it, or in other words: that every element is greater than or equal to the one before it. share | improve this answer.