uploaded at 2022. 12. 30. 오전 2:55:24

programmers/유사 칸토어 비트열/solution.java

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+// [문제 링크]: https://school.programmers.co.kr/learn/courses/30/lessons/148652
+
+class Solution {
+    private int bits(long index){
+        String bar = "11011";
+        int answer = 0, base = 1;
+        if(index <= 5){
+            for(int a = 0; a < index; a++) if(bar.charAt(a)=='1') answer++;
+            return answer;
+        }
+        while(Math.pow(5,base+1)<index) base++;
+        int section = (int)(index / (long)Math.pow(5,base));
+        int remainder = (int)(index % (long)Math.pow(5,base));
+        answer = section * (int)Math.pow(4,base);
+        if(section >= 3) answer -= (int)Math.pow(4,base);
+        if(section == 2) return answer;
+        else return answer + bits(remainder);
+    }
+    public int solution(int n, long l, long r) {
+        return bits(r)-bits(l-1);
+    }
+}