Problem:
Score : 500 points

Problem Statement

Takahashi has decided to work on K days of his choice from the N days starting with tomorrow.

You are given an integer C and a string S. Takahashi will choose his workdays as follows:

After working for a day, he will refrain from working on the subsequent C days.

If the i-th character of S is x, he will not work on Day i, where Day 1 is tomorrow, Day 2 is the day after tomorrow, and so on.

Find all days on which Takahashi is bound to work.

Constraints

1 \leq N \leq 2 \times 10^5

1 \leq K \leq N

0 \leq C \leq N

The length of S is N.

Each character of S is o or x.

Takahashi can choose his workdays so that the conditions in Problem Statement are satisfied.

Input

Input is given from Standard Input in the following format:

N K C
S

Output

Print all days on which Takahashi is bound to work in ascending order, one per line.

Sample Input 1

11 3 2
ooxxxoxxxoo

Sample Output 1

6

Takahashi is going to work on 3 days out of the 11 days. After working for a day, he will refrain from working on the subsequent 2 days.

There are four possible choices for his workdays: Day 1,6,10, Day 1,6,11, Day 2,6,10, and Day 2,6,11.

Thus, he is bound to work on Day 6.

Sample Input 2

5 2 3
ooxoo

Sample Output 2

1
5

There is only one possible choice for his workdays: Day 1,5.

Sample Input 3

5 1 0
ooooo

Sample Output 3

There may be no days on which he is bound to work.

Sample Input 4

16 4 3
ooxxoxoxxxoxoxxo

Sample Output 4

11
16

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)


import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;

public class Main {
    public static void main(String [] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int k = scanner.nextInt();
        int c = scanner.nextInt();
        String s = scanner.next();
        int[] dpLeftToRight = new int[n];
        dpLeftToRight[0] = s.charAt(0) == 'x' ? 0 : 1;
        for (int i = 1; i < s.length(); ++i) {
            if (s.charAt(i) == 'x') {
                dpLeftToRight[i] = dpLeftToRight[i - 1];
            } else {
                if (i - c - 1 >= 0) {
                    dpLeftToRight[i] = Math.max(dpLeftToRight[i - 1], dpLeftToRight[i - c - 1] + 1);
                } else {
                    dpLeftToRight[i] = Math.max(dpLeftToRight[i - 1], 1);
                }
            }
        }
        if (dpLeftToRight[n - 1] > k || dpLeftToRight[n - 1] < k) {
            return;
        }
        Map<Integer, Set<Integer>> workDaysToDayLeftToRight = new HashMap<>();
        for (int i = 0; i < n; ++i) {
            if (s.charAt(i) == 'x') {
                continue;
            }
            int workDays = dpLeftToRight[i];
            if (!workDaysToDayLeftToRight.containsKey(workDays)) {
                workDaysToDayLeftToRight.put(workDays, new HashSet<>());
            }
            workDaysToDayLeftToRight.get(workDays).add(i + 1);
        }
        int[] dpRightToLeft = new int[n];
        dpRightToLeft[n - 1] = s.charAt(n - 1) == 'x' ? 0 : 1;
        for (int i = s.length() - 2; i >= 0; --i) {
            if (s.charAt(i) == 'x') {
                dpRightToLeft[i] = dpRightToLeft[i + 1];
            } else {
                if (i + c + 1 < n) {
                    dpRightToLeft[i] = Math.max(dpRightToLeft[i + 1], dpRightToLeft[i + c + 1] + 1);
                } else {
                    dpRightToLeft[i] = Math.max(dpRightToLeft[i + 1], 1);
                }
            }
        }
        Map<Integer, Set<Integer>> workDaysToDayRightToLeft = new HashMap<>();
        for (int i = 0; i < n; ++i) {
            if (s.charAt(i) == 'x') {
                continue;
            }
            int workDays = dpRightToLeft[i];
            if (!workDaysToDayRightToLeft.containsKey(workDays)) {
                workDaysToDayRightToLeft.put(workDays, new HashSet<>());
            }
            workDaysToDayRightToLeft.get(workDays).add(i + 1);
        }

        Set<Integer> ans = new TreeSet<>();
        for (int i = 1; i <= n; ++i) {
            if (workDaysToDayLeftToRight.containsKey(i) && workDaysToDayLeftToRight.get(i).size() == 1) {
                ans.add(workDaysToDayLeftToRight.get(i).iterator().next());
            }
            if (workDaysToDayRightToLeft.containsKey(i) && workDaysToDayRightToLeft.get(i).size() == 1) {
                ans.add(workDaysToDayRightToLeft.get(i).iterator().next());
            }
        }
        for (int day: ans) {
            System.out.println(day);
        }
    }
}