1333D - Challenges in school №41 - CodeForces Solution

def main():
    
    n, k = readIntArr()
    a = list(input())
    
    batch = []
    for i in range(n - 1):
        if a[i] == 'R' and a[i + 1] == 'L':
            batch.append(i)
    allmoves = []
    while len(batch) > 0:
        allmoves.append(batch)
        for i in batch:
            a[i], a[i + 1] = a[i + 1], a[i]
        
        batch2 = set()
        for i in batch:
            i -= 1
            if i >= 0 and a[i] == 'R' and a[i + 1] == 'L':
                batch2.add(i)
            i += 2
            if i + 1 < n and a[i] == 'R' and a[i + 1] == 'L':
                batch2.add(i)
        batch = list(batch2)
    min_moves = len(allmoves)
    max_moves = sum([len(moves) for moves in allmoves])
    if not min_moves <= k <= max_moves:
        print(-1)
        return
    
        allans = []
    before = 0
    after = len(allmoves)
    for moves in allmoves:
        after -= 1
        l = len(moves)
        nmoves = min(l, k - before - after)
        for i in range(nmoves - 1):
            allans.append((1, moves[i] + 1))
            before += 1
        arr = [len(moves) - (nmoves - 1)]
        for i in range(nmoves - 1, len(moves)):
            arr.append(moves[i] + 1)
        before += 1
        allans.append(tuple(arr))
        if len(allans) > 1000000:
            multiLineArrayOfArraysPrint(allans)
            allans = []
    if allans:
        multiLineArrayOfArraysPrint(allans)
    
    return

import sys
input=lambda: sys.stdin.readline().rstrip("\r\n")  
def oneLineArrayPrint(arr):
    print(' '.join([str(x) for x in arr]))
def multiLineArrayPrint(arr):
    print('\n'.join([str(x) for x in arr]))
def multiLineArrayOfArraysPrint(arr):
    print('\n'.join([' '.join([str(x) for x in y]) for y in arr]))
 
def readIntArr():
    return [int(x) for x in input().split()]
 
def makeArr(defaultValFactory,dimensionArr):     dv=defaultValFactory;da=dimensionArr
    if len(da)==1:return [dv() for _ in range(da[0])]
    else:return [makeArr(dv,da[1:]) for _ in range(da[0])]
 
def queryInteractive(a, b):
    print('? {} {}'.format(a, b))
    sys.stdout.flush()
    return int(input())
 
def answerInteractive(ans):
    print('! {}'.format(ans))
    sys.stdout.flush()
 
inf=float('inf')
 
from math import gcd,floor,ceil
import math
 
for _abc in range(1):
    main()