Given an integer array arr, find, for every position, the value of the nearest element strictly smaller than it to its right — or -1 if no such element exists. This is the mirror image of finding the nearest smaller element to the left: the same monotonic-stack idea applies, just scanning from the end of the array backward instead of from the start forward. A stack kept in increasing order from bottom to top, with anything greater-or-equal popped off before each new value is pushed, gives every position its answer in O(1) amortized work — a smaller value discovered closer to a position permanently rules out any larger value farther away from ever being the answer, regardless of which direction the scan runs.