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Extract common sort logic to SortUtils class

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This commit is contained in:
William Brawner 2018-10-10 19:27:50 -05:00
parent 036d2f400c
commit ea4f641ae2
4 changed files with 48 additions and 37 deletions
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6
sorting/src/main/java/com/wbrawner/algorithms/sorting/BubbleSort.java
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@ -1,5 +1,7 @@
package com.wbrawner.algorithms.sorting;
import static com.wbrawner.algorithms.sorting.SortUtils.swap;
/**
* The Bubble Sort algorithm modifies an array in place, continuously
* looping through the array and swapping elements that are unsorted until no
@ -23,9 +25,7 @@ public class BubbleSort {
swapsMade = false;
for (int i = 1; i < array.length; i++) {
if (array[i] < array[i - 1]) {
int currentValue = array[i];
array[i] = array[i - 1];
array[i - 1] = currentValue;
swap(array, i, i - 1);
swapsMade = true;
}
}

33
sorting/src/main/java/com/wbrawner/algorithms/sorting/MergeSort.java
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@ -2,6 +2,8 @@ package com.wbrawner.algorithms.sorting;
import java.util.Arrays;
import static com.wbrawner.algorithms.sorting.SortUtils.merge;
/**
* The Merge Sort algorithm works by the "divide and conquer" strategy. The
* given array of data is recursively split into two smaller arrays that are
@ -31,35 +33,4 @@ public class MergeSort {
sort(second)
);
}
private static int[] merge(int[] first, int[] second) {
// Create a new array that can hold both of the given arrays
int[] sorted = new int[first.length + second.length];
// Three values are used here:
// i - keeps track of the sorted array's index
// j - keeps track of the first array's index
// k - keeps track of the second array's index
int i, j = 0, k = 0;
for (i = 0; i < sorted.length; i++) {
// If we still have values from the first array...
if (j < first.length
// ... and we either don't have values from the second
// array or the value at the current index of the first
// array is less than the value at the current index of
// the second array...
&& (k >= second.length || first[j] < second[k])
) {
// ... then we append the value at the current index of the
// first array to the sorted array.
sorted[i] = first[j];
j++;
} else if (k < second.length) {
// In any other case, we should add the value at the current
// index of the second array
sorted[i] = second[k];
k++;
}
}
return sorted;
}
}

6
sorting/src/main/java/com/wbrawner/algorithms/sorting/SelectionSort.java
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@ -1,5 +1,7 @@
package com.wbrawner.algorithms.sorting;
import static com.wbrawner.algorithms.sorting.SortUtils.swap;
/**
* The Selection Sort algorithm modifies an array in place, finding the
* minimum value that hasn't been sorted, and swapping it with the first
@ -25,9 +27,7 @@ public class SelectionSort {
minPos = j;
}
}
int min = array[minPos];
array[minPos] = array[i];
array[i] = min;
swap(array, minPos, i);
}
return array;

40
sorting/src/main/java/com/wbrawner/algorithms/sorting/SortUtils.java Normal file
View file

@ -0,0 +1,40 @@
package com.wbrawner.algorithms.sorting;
public class SortUtils {
public static int[] merge(int[] first, int[] second) {
// Create a new array that can hold both of the given arrays
int[] sorted = new int[first.length + second.length];
// Three values are used here:
// i - keeps track of the sorted array's index
// j - keeps track of the first array's index
// k - keeps track of the second array's index
int i, j = 0, k = 0;
for (i = 0; i < sorted.length; i++) {
// If we still have values from the first array...
if (j < first.length
// ... and we either don't have values from the second
// array or the value at the current index of the first
// array is less than the value at the current index of
// the second array...
&& (k >= second.length || first[j] < second[k])
) {
// ... then we append the value at the current index of the
// first array to the sorted array.
sorted[i] = first[j];
j++;
} else if (k < second.length) {
// In any other case, we should add the value at the current
// index of the second array
sorted[i] = second[k];
k++;
}
}
return sorted;
}
public static void swap(int[] array, int firstPos, int secondPos) {
int firstValue = array[firstPos];
array[firstPos] = array[secondPos];
array[secondPos] = firstValue;
}
}