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DP_10942.java
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DP_10942.java
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// https://www.acmicpc.net/problem/10942
// DP 동적계획법 - 팰린드롬(Palindrome)
// Memoization : num[start] == num[end] 이면 -> dp[s][e] = 1 저장
package stepbystep;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;
public class DP_10942 {
static int[] num;
static int[][] dp; // dp[i][j] = i ~ j 번 수열이 팰린드롬인지 저장
public static void main(String[] args) throws IOException {
// Input (1 <= N <= 2000)
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int N = Integer.parseInt(br.readLine()); // 수열의 크기
num = new int[N+1];
StringTokenizer st = new StringTokenizer(br.readLine());
for (int i=1; i<N+1; i++) {
num[i] = Integer.parseInt(st.nextToken());
}
dp = new int[N+1][N+1];
for (int e[] : dp) {
Arrays.fill(e, -1); // 아직 계산되지 않은 dp배열은 -1로 초기화
}
// Question (1 <= M <= 1000000)
StringBuilder sb = new StringBuilder();
int M = Integer.parseInt(br.readLine()); // 질문의 개수
for (int i=0; i<M; i++) {
st = new StringTokenizer(br.readLine());
int start = Integer.parseInt(st.nextToken());
int end = Integer.parseInt(st.nextToken());
if ( isPalindrome(start, end) == 1 ) sb.append("1\n");
else sb.append("0\n");
}
System.out.println(sb);
}
// Recursive
static int isPalindrome(int start, int end) {
if (start >= end) return 1;
// 이미 계산된 값이면..
if (dp[start][end] != -1)
return dp[start][end];
if (num[start] == num[end]) {
return dp[start][end] = isPalindrome(start+1, end-1);
}
return 0;
}
}