RU-ALLRUSSIAN 1981 Problem 4
Write down a row of arbitrary integers (repetitions allowed). Now construct a second row as follows. Suppose the integer n is in column k in the first row. In column k in the second row write down the number of occurrences of n in row 1 in columns 1 to k inclusive. Similarly, construct a third row under the second row (using the values in the second row), and a fourth row. An example follows:
Show that the fourth row is always the same as the second row.
Dataset text NuminaMath olympiads. Quoted with source.
Solutions
No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.