Larger Score

AtCoder

IDarc138_a

Time3000ms

Memory256MB

Difficulty—

We have an integer sequence of length $N$: $A=(A_1,A_2,\cdots,A_N)$. Below in this problem, let the **score** of $A$ be the sum of the first $K$ terms of $A$. Additionally, let $s$ be the score of the sequence $A$ given in input. You can do the following operation any number of times. * Choose two adjacent elements of $A$ and swap them. Your objective is to make the score at least $s+1$. Determine whether the objective is achievable. If it is, find the minimum number of operations needed to achieve it. ## Constraints * $2 \leq N \leq 4 \times 10^5$ * $1 \leq K \leq N-1$ * $1 \leq A_i \leq 10^9$ * All values in input are integers. ## Input Input is given from Standard Input in the following format: $N$ $K$ $A_1$ $A_2$ $\cdots$ $A_N$ [samples]

Samples

Input #1

4 2
2 1 1 2

Output #1

2

We have $s=2+1=3$. The following sequence of operations makes the score at least $4$.

*   $(2,1,1,2) \to ($swap $A_3$ and $A_4)\to (2,1,2,1) \to ($swap $A_2$ and $A_3)\to (2,2,1,1)$

The objective is not achievable in one operation, so the minimum number of operations needed is $2$.

Input #2

3 1
3 2 1

Output #2

\-1

Input #3

20 13
90699850 344821203 373822335 437633059 534203117 523743511 568996900 694866636 683864672 836230375 751240939 942020833 865334948 142779837 22252499 197049878 303376519 366683358 545670804 580980054

Output #3

API Response (JSON)

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  "problem": {
    "name": "Larger Score",
    "description": {
      "content": "We have an integer sequence of length $N$: $A=(A_1,A_2,\\cdots,A_N)$. Below in this problem, let the **score** of $A$ be the sum of the first $K$ terms of $A$. Additionally, let $s$ be the score of the",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 3000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "arc138_a"
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  "statements": [
    {
      "statement_type": "Markdown",
      "content": "We have an integer sequence of length $N$: $A=(A_1,A_2,\\cdots,A_N)$. Below in this problem, let the **score** of $A$ be the sum of the first $K$ terms of $A$. Additionally, let $s$ be the score of the...",
      "is_translate": false,
      "language": "English"
    }
  ]
}

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