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using uint64_t from cstdint header

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and doxygen formatiing
This commit is contained in:
Rakshit Raj
2020-11-29 22:39:47 +05:30
committed by GitHub
parent 81560e8147
commit 047578bb0a
1 changed files with 30 additions and 29 deletions
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59
sorting/count_inversions.cpp
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@@ -10,11 +10,11 @@
* The count of inversions help to determine how close the array
* is to being sorted in ASCENDING order.
*
* two elements a[i] and a[j] form an inversion if a[i] > a[j] and i < j
* two elements a[i] and a[j] form an inversion if `a[i]` > `a[j]` and i < j
*
* Time Complexity --> O(n.log n)
* Time Complexity --> `O(n.log n)`
* Space Complexity --> O(n) ; additional array temp[1..n]
* Space Complexity --> `O(n)` ; additional array `temp[1..n]`
* ### Algorithm
* 1. The idea is similar to merge sort, divide the array into two equal or
@@ -43,6 +43,7 @@
#include <cassert>
#include <iostream>
#include <vector>
#include <cstdint>
/**
* @namespace sorting
@@ -71,18 +72,18 @@ namespace inversion {
*
* @param arr input array, data-menber of vector
* @param temp stores the resultant merged array
* @param left lower bound of arr[] and left-sub-array
* @param left lower bound of `arr[]` and left-sub-array
* @param mid midpoint, upper bound of left sub-array,
* (mid+1) gives the lower bound of right-sub-array
* @param right upper bound of arr[] and right-sub-array
* `(mid+1)` gives the lower bound of right-sub-array
* @param right upper bound of `arr[]` and right-sub-array
* @returns number of inversions found in merge step
*/
template <typename T>
int merge(T* arr, T* temp, int left, int mid, int right) {
int i = left; /* i --> index of left sub-array */
int j = mid + 1; /* j --> index for right sub-array */
int k = left; /* k --> index for resultant array temp */
int inv_count = 0; // inversion count
uint64_t merge(T* arr, T* temp, uint64_t left, uint64_t mid, uint64_t right) {
uint64_t i = left; /* i --> index of left sub-array */
uint64_t j = mid + 1; /* j --> index for right sub-array */
uint64_t k = left; /* k --> index for resultant array temp */
uint64_t inv_count = 0; // inversion count
while ((i <= mid) && (j <= right)) {
if (arr[i] <= arr[j]) {
@@ -123,8 +124,8 @@ int merge(T* arr, T* temp, int left, int mid, int right) {
* @returns number of inversions in array
*/
template <typename T>
int mergeSort(T* arr, T* temp, int left, int right) {
int mid = 0, inv_count = 0;
uint64_t mergeSort(T* arr, T* temp, uint64_t left, uint64_t right) {
uint64_t mid = 0, inv_count = 0;
if (right > left) {
// midpoint to split the array
mid = (right + left) / 2;
@@ -154,7 +155,7 @@ int mergeSort(T* arr, T* temp, int left, int right) {
* @returns number of inversions in input array, sorts the array
*/
template <class T>
int countInversion(T* arr, const int size) {
int countInversion(T* arr, const uint64_t size) {
std::vector<T> temp;
temp.reserve(size);
temp.assign(size, 0);
@@ -169,9 +170,9 @@ int countInversion(T* arr, const int size) {
*
*/
template <typename T>
void show(T* arr, const int array_size) {
void show(T* arr, const uint64_t array_size) {
std::cout << "Printing array: \n";
for (int i = 0; i < array_size; i++) {
for (uint64_t i = 0; i < array_size; i++) {
std::cout << " " << arr[i];
}
std::cout << "\n";
@@ -186,35 +187,35 @@ void show(T* arr, const int array_size) {
*/
static void test() {
// Test 1
std::vector<int> arr1 = {
std::vector<uint64_t> arr1 = {
100, 99, 98, 97, 96, 95, 94, 93, 92, 91, 90, 89, 88, 87, 86, 85, 84,
83, 82, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69, 68, 67,
66, 65, 64, 63, 62, 61, 60, 59, 58, 57, 56, 55, 54, 53, 52, 51, 50,
49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33,
32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16,
15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
int size1 = arr1.size();
int inv_count1 = 4950;
int result1 = sorting::inversion::countInversion(arr1.data(), size1);
uint64_t size1 = arr1.size();
uint64_t inv_count1 = 4950;
uint64_t result1 = sorting::inversion::countInversion(arr1.data(), size1);
assert(inv_count1 == result1);
// Test 2
std::vector<int> arr2 = {22, 66, 75, 23, 11, 87, 2, 44, 98, 43};
int size2 = arr2.size();
int inv_count2 = 20;
int result2 = sorting::inversion::countInversion(arr2.data(), size2);
uint64_t size2 = arr2.size();
uint64_t inv_count2 = 20;
uint64_t result2 = sorting::inversion::countInversion(arr2.data(), size2);
assert(inv_count2 == result2);
// Test 3
std::vector<double> arr3 = {33.1, 45.2, 65.4, 76.5, 1.0,
2.9, 5.4, 7.7, 88.9, 12.4};
int size3 = arr3.size();
int inv_count3 = 21;
int result3 = sorting::inversion::countInversion(arr3.data(), size3);
uint64_t size3 = arr3.size();
uint64_t inv_count3 = 21;
uint64_t result3 = sorting::inversion::countInversion(arr3.data(), size3);
assert(inv_count3 == result3);
// Test 4
std::vector<char> arr4 = {'a', 'b', 'c', 'd', 'e'};
int size4 = arr4.size();
int inv_count4 = 0;
int result4 = sorting::inversion::countInversion(arr4.data(), size4);
uint64_t size4 = arr4.size();
uint64_t inv_count4 = 0;
uint64_t result4 = sorting::inversion::countInversion(arr4.data(), size4);
assert(inv_count4 == result4);
}