My Last ABC Problem

AtCoder

IDagc059_a

Time2000ms

Memory256MB

Difficulty—

Consider a string $t$ consisting only of characters `A`, `B`, and `C`. We can do the following operation with it: * Choose any substring $t[l:r]$ and any permutation $(X, Y, Z)$ of characters $($`A`$,$`B`$,$`C`$)$. Here, $t[l:r]$ denotes the substring formed by the $l$\-th through the $r$\-th characters of $t$, where $l$ and $r$ are of your choice. Then, replace each character `A`, `B`, and `C` in $t[l:r]$ by $X$, $Y$, and $Z$, respectively. For example, for a string $t = $ `ACBAAC`, we can choose a substring $t[3:6]$ and $(X,Y,Z)=($`C`$,$`B`$,$`A`$)$. After this operation, the string will become `ACBCCA`. Alina likes strings in which all characters are the same. She defines the beauty of a string $t$ as the minimum number of operations required to make all its characters equal. You are given a string $S$ of length $N$ consisting only of characters `A`, `B`, and `C`. Answer $Q$ queries. The $i$\-th query is the following: * Given integers $L_i$ and $R_i$, find the beauty of the substring $t=S[L_i:R_i]$. ## Constraints * $1 \le N \le 10^5$ * $S$ is a string of length $N$ consisting only of characters `A`, `B`, and `C`. * $1 \le Q \le 10^5$ * $1 \le L_i \le R_i \le N$ * All numbers in the input are integers. ## Input Input is given from Standard Input in the following format: $N$ $Q$ $S$ $L_1$ $R_1$ $L_2$ $R_2$ $\vdots$ $L_Q$ $R_Q$ [samples]

Samples

Input #1

6 4
ABCCCA
3 5
2 3
1 3
1 6

Output #1

0
1
2
2

In the first query, the string is $t = $ `CCC`, in which all letters are already equal. The answer is $0$.
In the second query, the string is $t = $ `BC`. We can change it to `BB` in one operation, by choosing a substring $t[2:2]$ and $(X,Y,Z)=($`A`$,$`C`$,$`B`$)$.
In the third query, the string is $t = $ `ABC`. We can change it to `AAB` in one operation, by choosing a substring $t[2:3]$ and $(X,Y,Z)=($`C`$,$`A`$,$`B`$)$, and then to `BBB` in the next operation, by choosing a substring $t[1:2]$ and $(X,Y,Z)=($`B`$,$`A`$,$`C`$)$.

API Response (JSON)

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    "name": "My Last ABC Problem",
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      "content": "Consider a string $t$ consisting only of characters `A`, `B`, and `C`. We can do the following operation with it: *   Choose any substring $t[l:r]$ and any permutation $(X, Y, Z)$ of characters $($`A",
      "description_type": "Markdown"
    },
    "platform": "AtCoder",
    "limit": {
      "time_limit": 2000,
      "memory_limit": 262144
    },
    "difficulty": "None",
    "is_remote": true,
    "is_sync": true,
    "sync_url": null,
    "sign": "agc059_a"
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    {
      "statement_type": "Markdown",
      "content": "Consider a string $t$ consisting only of characters `A`, `B`, and `C`. We can do the following operation with it:\n\n*   Choose any substring $t[l:r]$ and any permutation $(X, Y, Z)$ of characters $($`A...",
      "is_translate": false,
      "language": "English"
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