ALGORITHM/BOJ
[백준] 10816 숫자 카드 2
0298
2021. 9. 29. 23:30
https://www.acmicpc.net/problem/10816
10816번: 숫자 카드 2
첫째 줄에 상근이가 가지고 있는 숫자 카드의 개수 N(1 ≤ N ≤ 500,000)이 주어진다. 둘째 줄에는 숫자 카드에 적혀있는 정수가 주어진다. 숫자 카드에 적혀있는 수는 -10,000,000보다 크거나 같고, 10,
www.acmicpc.net
2021-09-27
1) HashMap
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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.StringTokenizer;
public class Main10816 {
public static int N, M;
public static HashMap<Integer, Integer> map;
public static StringBuilder sb;
public static void main(String[] args) throws IOException {
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer(bf.readLine().trim());
sb = new StringBuilder();
N = Integer.parseInt(st.nextToken());
map = new HashMap<>();
st = new StringTokenizer(bf.readLine());
for(int i = 0; i < N; i++) {
int num = Integer.parseInt(st.nextToken());
map.put(num, map.getOrDefault(num, 0) + 1);
}
st = new StringTokenizer(bf.readLine().trim());
M = Integer.parseInt(st.nextToken());
st = new StringTokenizer(bf.readLine());
for(int i = 0; i < M; i++) {
int num = Integer.parseInt(st.nextToken());
if(map.containsKey(num)) sb.append(map.get(num)).append(" ");
else sb.append("0").append(" ");
}
System.out.println(sb.toString());
}
}
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cs |
2) 이진탐색 (Lower Bound, Upper Bound)
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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;
public class Main {
public static int N, M;
public static int[] arr;
public static StringBuilder sb;
public static int upperbound(int num) {
int start = 0;
int end = arr.length;
while(start < end) {
int mid = (start + end) >> 1;
if(arr[mid] > num) end = mid;
else start = mid + 1;
}
return start;
}
public static int lowerbound(int num) {
int start = 0;
int end = arr.length;
while(start < end) {
int mid = (start + end) >> 1;
if(arr[mid] >= num) end = mid;
else start = mid + 1;
}
return end;
}
public static void main(String[] args) throws IOException {
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer(bf.readLine().trim());
sb = new StringBuilder();
N = Integer.parseInt(st.nextToken());
st = new StringTokenizer(bf.readLine());
arr = new int[N];
for(int i = 0; i < N; i++) {
int num = Integer.parseInt(st.nextToken());
arr[i] = num;
}
Arrays.sort(arr);
st = new StringTokenizer(bf.readLine().trim());
M = Integer.parseInt(st.nextToken());
st = new StringTokenizer(bf.readLine());
for(int i = 0; i < M; i++) {
int num = Integer.parseInt(st.nextToken());
int up = upperbound(num);
if(up < 0) sb.append("0").append(" ");
else sb.append(up - lowerbound(num)).append(" ");
}
System.out.println(sb.toString());
}
}
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#문제풀이
HashMap과 이진탐색(Lower bound, Upper bound) 로 풀었다.