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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,125 @@ | ||
| package test.boj.dp; | ||
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| import org.junit.*; | ||
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| import java.io.*; | ||
| import java.util.StringTokenizer; | ||
| import java.util.stream.IntStream; | ||
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| import static org.assertj.core.api.Assertions.assertThat; | ||
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| // https://cheolhojung.github.io/posts/algorithm/boj-biotonic-partial-sequence.html | ||
| public class m_가장_긴_바이토닉_부분_수열 { | ||
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| public static void main(String[] args) throws IOException { | ||
| BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); | ||
| BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out)); | ||
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| int n = Integer.parseInt(br.readLine()); | ||
| BitonicSubSequence biTonicSubNumbers = new BitonicSubSequence(n, br.readLine()); | ||
| System.out.println(biTonicSubNumbers.maxLength()); | ||
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| bw.flush(); | ||
| bw.close(); | ||
| br.close(); | ||
| } | ||
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| @Test | ||
| public void test() { | ||
| assertThat(solution(1, "1")) | ||
| .isEqualTo(1); | ||
| assertThat(solution(10, "1 5 2 1 4 3 4 5 2 1")) | ||
| .isEqualTo(7); | ||
| assertThat(solution(7, "10 5 10 20 10 30 5")) | ||
| .isEqualTo(5); | ||
| } | ||
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| private int solution(int n, String numbers) { | ||
| BitonicSubSequence biTonicSubNumbers = new BitonicSubSequence(n, numbers); | ||
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| return biTonicSubNumbers.maxLength(); | ||
| } | ||
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| static class BitonicSubSequence { | ||
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| private static final int MAX_LENGTH = 1000; | ||
| private static final int PREV_SMALLER = 0; | ||
| private static final int NEXT_SMALLER = 1; | ||
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| private final int n; | ||
| private final int[] numbers; | ||
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| private int[][] dp; | ||
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| public BitonicSubSequence(int n, String numbers) { | ||
| this.n = n; | ||
| this.numbers = new int[n + 2]; | ||
| this.dp = new int[2][MAX_LENGTH + 1]; | ||
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| StringTokenizer tokenizer = new StringTokenizer(numbers); | ||
| for (int i = 1; i <= n; i++) { | ||
| this.numbers[i] = Integer.parseInt(tokenizer.nextToken()); | ||
| } | ||
| } | ||
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| public int maxLength() { | ||
| int result = Integer.MIN_VALUE; | ||
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| for (int i = 1; i <= n; i++) { | ||
| dp[PREV_SMALLER][i] = maxLengthPrevSmallerNumbers(i) + 1; | ||
| } | ||
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| for (int i = n; i >= 1; i--) { | ||
| dp[NEXT_SMALLER][i] = maxLengthNextSmallerNumbers(i) + 1; | ||
| result = Math.max(result, dp[NEXT_SMALLER][i] + dp[PREV_SMALLER][i] - 1); | ||
| } | ||
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| return result; | ||
| } | ||
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| private int maxLengthNextSmallerNumbers(int i) { | ||
| return maxRangeClosed(i + 1, n, i, NEXT_SMALLER); | ||
| } | ||
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| private int maxLengthPrevSmallerNumbers(int i) { | ||
| return maxRangeClosed(1, i - 1, i, PREV_SMALLER); | ||
| } | ||
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| private int maxRangeClosed(int start, int end, int i, int SMALLER_INDEX) { | ||
| return IntStream.rangeClosed(start, end) | ||
| .map(j -> max(i, j, SMALLER_INDEX)) | ||
| .max() | ||
| .orElse(0); | ||
| } | ||
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| private int max(int i, int j, int SMALLER_INDEX) { | ||
| if (this.numbers[i] > this.numbers[j]) { | ||
| return dp[SMALLER_INDEX][j]; | ||
| } | ||
| return 0; | ||
| } | ||
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| // private int maxLengthNextSmallerNumbers2(int i) { | ||
| // int result = 0; | ||
| // for (int j = i + 1; j <= n; j++) { | ||
| // result = max(result, i, j, NEXT_SMALLER); | ||
| // } | ||
| // return result; | ||
| // } | ||
| // | ||
| // private int maxLengthPrevSmallerNumbers2(int i) { | ||
| // int result = 0; | ||
| // for (int j = i - 1; j >= 1; j--) { | ||
| // result = max(result, i, j, PREV_SMALLER); | ||
| // } | ||
| // return result; | ||
| // } | ||
| // | ||
| // private int max(int result, int i, int j, int SMALLER_INDEX) { | ||
| // if (this.numbers[i] > this.numbers[j]) { | ||
| // return Math.max(result, dp[SMALLER_INDEX][j]); | ||
| // } | ||
| // return result; | ||
| // } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,89 @@ | ||
| package test.boj.dp; | ||
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| import org.junit.*; | ||
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| import java.io.*; | ||
| import java.util.StringTokenizer; | ||
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| import static org.assertj.core.api.Assertions.assertThat; | ||
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| public class n_연속합 { | ||
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| public static void main(String[] args) throws IOException { | ||
| BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); | ||
| BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out)); | ||
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| int n = Integer.parseInt(br.readLine()); | ||
| ContinuousSum continuousSum = new ContinuousSum(n, br.readLine()); | ||
| System.out.println(continuousSum.max()); | ||
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| bw.flush(); | ||
| bw.close(); | ||
| br.close(); | ||
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| } | ||
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| @Test | ||
| public void test() { | ||
| assertThat(solution(10, "10 -4 3 1 5 6 -35 12 21 -1")) | ||
| .isEqualTo(33); | ||
| assertThat(solution(1, "1")) | ||
| .isEqualTo(1); | ||
| assertThat(solution(1, "-1000")) | ||
| .isEqualTo(-1000); | ||
| assertThat(solution(2, "-2000 -1000")) | ||
| .isEqualTo(-1000); | ||
| assertThat(solution(2, "-1000 -2000")) | ||
| .isEqualTo(-1000); | ||
| assertThat(solution(3, "-1000 5 1000")) | ||
| .isEqualTo(1005); | ||
| assertThat(solution(5, "-3 -1 2 -1 5")) | ||
| .isEqualTo(6); | ||
| } | ||
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| private int solution(int n, String numbers) { | ||
| ContinuousSum continuousSum = new ContinuousSum(n, numbers); | ||
| return continuousSum.max(); | ||
| } | ||
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| static class ContinuousSum { | ||
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| private final int n; | ||
| private final int[] numbers; | ||
| private final int[] dp; | ||
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| public ContinuousSum(int n, String numbers) { | ||
| this.n = n; | ||
| this.dp = new int[n + 1]; | ||
| this.numbers = new int[n + 1]; | ||
| StringTokenizer tokenizer = new StringTokenizer(numbers); | ||
| for (int i = 1; i <= n; i++) { | ||
| this.numbers[i] = Integer.parseInt(tokenizer.nextToken()); | ||
| } | ||
| } | ||
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| // 현재 숫자를 이전 숫자까지의 합과 더한 경우와 | ||
| // 현재 숫자부터 시작하는 경우로 나눌 수 있음 | ||
| // dp[i - 1] + this.numbers[i]: 현재 숫자를 이전 숫자까지의 합과 더한 경우 | ||
| // this.numbers[i]: 현재 숫자부터 시작하는 경우 | ||
| // -1000 5 1000 | ||
| // dp -1000 5 1005 | ||
| // O -1005 1005 | ||
| // X 5 1000 | ||
| public int max() { | ||
| int result = this.numbers[1]; | ||
| dp[1] = this.numbers[1]; | ||
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| for (int i = 2; i <= n; i++) { | ||
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| dp[i] = Math.max( | ||
| dp[i - 1] + this.numbers[i], | ||
| this.numbers[i] | ||
| ); | ||
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| result = Math.max(result, dp[i]); | ||
| } | ||
| return result; | ||
| } | ||
| } | ||
| } |