P1097 [NOIP 2007 Senior] Counting Numbers

In a research survey, $n$ natural numbers were collected, each not exceeding $1.5 \times 10^9$. It is known that the number of distinct values does not exceed $10^4$. Now you need to count how many times each natural number appears and output the results in ascending order of the numbers.

There are $n+1$ lines in total. - The first line contains an integer $n$, the number of natural numbers. - Lines $2$ to $n+1$ each contain one natural number.

Output $m$ lines in total (where $m$ is the number of distinct numbers among the $n$ natural numbers), in ascending order of the numbers. Each line outputs $2$ integers: the natural number and the number of times it appears, separated by a single space.

- 30% of the testdata satisfy: $1 \le n \le 1000$. - 60% of the testdata satisfy: $1 \le n \le 50000$. - 100% of the testdata satisfy: $1 \le n \le 200000$, and each number does not exceed $1.5 \times 10^9$. NOIP 2007 Senior, Problem 1. Translated by ChatGPT 5