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Merge pull request #8084 from dupirefr/bael-3348

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dupirefr/dupire.francois+pro@gmail.com [BAEL-3348] Smallest missing positive integer in an array
This commit is contained in:
Erik Pragt 2019-11-07 08:56:18 +11:00 committed by GitHub
commit 289c3e4c34
2 changed files with 125 additions and 0 deletions
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37
algorithms-miscellaneous-4/src/main/java/com/baeldung/algorithms/smallestinteger/SmallestMissingPositiveInteger.java Normal file
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package com.baeldung.algorithms.smallestinteger;
import java.util.Arrays;
public class SmallestMissingPositiveInteger {
public static int searchInSortedArray(int[] input) {
for (int i = 0; i < input.length; i++) {
if (i != input[i]) {
return i;
}
}
return input.length;
}
public static int searchInUnsortedArraySortingFirst(int[] input) {
Arrays.sort(input);
return searchInSortedArray(input);
}
public static int searchInUnsortedArrayBooleanArray(int[] input) {
boolean[] flags = new boolean[input.length];
for (int number : input) {
if (number < flags.length) {
flags[number] = true;
}
}
for (int i = 0; i < flags.length; i++) {
if (!flags[i]) {
return i;
}
}
return flags.length;
}
}

88
algorithms-miscellaneous-4/src/test/java/com/baeldung/algorithms/smallestinteger/SmallestMissingPositiveIntegerUnitTest.java Normal file
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package com.baeldung.algorithms.smallestinteger;
import org.junit.jupiter.api.Test;
import static org.assertj.core.api.Assertions.assertThat;
class SmallestMissingPositiveIntegerUnitTest {
@Test
void givenArrayWithThreeMissing_whenSearchInSortedArray_thenThree() {
int[] input = new int[] {0, 1, 2, 4, 5};
int result = SmallestMissingPositiveInteger.searchInSortedArray(input);
assertThat(result).isEqualTo(3);
}
@Test
void givenArrayWithOneAndThreeMissing_whenSearchInSortedArray_thenOne() {
int[] input = new int[] {0, 2, 4, 5};
int result = SmallestMissingPositiveInteger.searchInSortedArray(input);
assertThat(result).isEqualTo(1);
}
@Test
void givenArrayWithoutMissingInteger_whenSearchInSortedArray_thenArrayLength() {
int[] input = new int[] {0, 1, 2, 3, 4, 5};
int result = SmallestMissingPositiveInteger.searchInSortedArray(input);
assertThat(result).isEqualTo(input.length);
}
@Test
void givenArrayWithThreeMissing_whenSearchInUnsortedArraySortingFirst_thenThree() {
int[] input = new int[] {1, 4, 0, 5, 2};
int result = SmallestMissingPositiveInteger.searchInUnsortedArraySortingFirst(input);
assertThat(result).isEqualTo(3);
}
@Test
void givenArrayWithOneAndThreeMissing_whenSearchInUnsortedArraySortingFirst_thenOne() {
int[] input = new int[] {4, 2, 0, 5};
int result = SmallestMissingPositiveInteger.searchInUnsortedArraySortingFirst(input);
assertThat(result).isEqualTo(1);
}
@Test
void givenArrayWithoutMissingInteger_whenSearchInUnsortedArraySortingFirst_thenArrayLength() {
int[] input = new int[] {4, 5, 1, 3, 0, 2};
int result = SmallestMissingPositiveInteger.searchInUnsortedArraySortingFirst(input);
assertThat(result).isEqualTo(input.length);
}
@Test
void givenArrayWithThreeMissing_whenSearchInUnsortedArrayBooleanArray_thenThree() {
int[] input = new int[] {1, 4, 0, 5, 2};
int result = SmallestMissingPositiveInteger.searchInUnsortedArrayBooleanArray(input);
assertThat(result).isEqualTo(3);
}
@Test
void givenArrayWithOneAndThreeMissing_whenSearchInUnsortedArrayBooleanArray_thenOne() {
int[] input = new int[] {4, 2, 0, 5};
int result = SmallestMissingPositiveInteger.searchInUnsortedArrayBooleanArray(input);
assertThat(result).isEqualTo(1);
}
@Test
void givenArrayWithoutMissingInteger_whenSearchInUnsortedArrayBooleanArray_thenArrayLength() {
int[] input = new int[] {4, 5, 1, 3, 0, 2};
int result = SmallestMissingPositiveInteger.searchInUnsortedArrayBooleanArray(input);
assertThat(result).isEqualTo(input.length);
}
}