[ICPC 2022 Jinan R] Quick Sort

Luogu

IDLGP9673

Time5000ms

Memory512MB

DifficultyP5

2022O2优化ICPC济南

When Prof. Pang was young, he wrote the following code for quick sort. Please calculate how many swaps are performed when calling $\text{quicksort}(A, 1, n)$. $A$ is a given permutation with length $n$. ![](https://cdn.luogu.com.cn/upload/image_hosting/8ig9i3bq.png) ## Input The first line contains one integer $T~(1\le T \le 10^5)$, the number of test cases. For each test case, the first line contains one positive integer $n~(1\le n \le 5\times 10^5)$. The next line contains $n$ integers $a_1,\ldots, a_n~(1 \le a_i\le n)$ denoting the permutation $A$. It is guaranteed that $a_1,\ldots, a_n$ form a permutation, i.e.~$a_i\neq a_j$ for $i \neq j$. It is guaranteed that the sum of $n$ over all test cases is no more than $5\times 10^5$. ## Output For each test case, output one line containing the number of swaps performed when calling $\text{quicksort}(A, 1, n)$. [samples]

Samples

Input #1

3
3
3 2 1
5
2 4 5 3 1
10
7 2 4 6 1 9 10 8 5 3

Output #1

1
4
7

API Response (JSON)

{
  "problem": {
    "name": "[ICPC 2022 Jinan R] Quick Sort",
    "description": {
      "content": "When Prof. Pang was young, he wrote the following code for quick sort. Please calculate how many swaps are performed when calling $\\text{quicksort}(A, 1, n)$. $A$ is a given permutation with length $n",
      "description_type": "Markdown"
    },
    "platform": "Luogu",
    "limit": {
      "time_limit": 5000,
      "memory_limit": 524288
    },
    "difficulty": {
      "LuoguStyle": "P5"
    },
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "LGP9673"
  },
  "statements": [
    {
      "statement_type": "Markdown",
      "content": "When Prof. Pang was young, he wrote the following code for quick sort. Please calculate how many swaps are performed when calling $\\text{quicksort}(A, 1, n)$. $A$ is a given permutation with length $n...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

Full JSON Raw Segments