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Rooted by: YourFirstSolution
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  • Description

    Given an array (vector, for C++) of n distinct integers in the range [0, n], find the one that is missing.

    First C++ solution; fixed up the test cases that were missing 0 (so those in the parent description wouldn't have worked), reworked to a vector for simplicity (could do the same op on an array + length combo, but it's just less idiomatic), simplified structure for the tests, and finally implemented an actual solution.

     Code 
    #include <vector>
#include <algorithm>
using namespace std;
int missingNumber(vector<int> nums) {
  nums.push_back(nums.size());
  for (int i = 0; i < static_cast<int>(nums.size()); i++) {
    if (find(nums.begin(), nums.end(), i) == nums.end()) return i;
  }
  return nums.size() - 1;
}
     Test Cases 
    #include <criterion/criterion.h>

int missingNumber(std::vector<int> nums);

Test(findMissingNumber, should_return_5_for_given_array) {
std::vector<int> arr{0, 1, 2, 3, 4, 6, 7, 8, 9, 10};
cr_assert_eq(missingNumber(arr), 5);
}

Test(findMissingNumber, should_return_2_for_given_array) {
std::vector<int> arr{0, 1, 3, 4, 5};
cr_assert_eq(missingNumber(arr), 2);
}
    View Run Output
  • Code
    • class Solution {
    • public:
    • int missingNumber(vector<int>& nums) {
    • }
    • };
    • #include <vector>
    • #include <algorithm>
    • using namespace std;
    • int missingNumber(vector<int> nums) {
    • nums.push_back(nums.size());
    • for (int i = 0; i < static_cast<int>(nums.size()); i++) {
    • if (find(nums.begin(), nums.end(), i) == nums.end()) return i;
    • }
    • return nums.size() - 1;
    • }
     Test Cases
    • #include <criterion/criterion.h>
    • // Function to find the missing number in an array of integers
    • int findMissingNumber(int arr[], int n) {
    • // Code to find the missing number
    • }
    • int missingNumber(std::vector<int> nums);
    • Test(findMissingNumber, should_return_5_for_given_array) {
    • int arr[] = {1, 2, 3, 4, 6, 7, 8, 9, 10};
    • int n = sizeof(arr) / sizeof(arr[0]);
    • cr_assert_eq(findMissingNumber(arr, n), 5);
    • std::vector<int> arr{0, 1, 2, 3, 4, 6, 7, 8, 9, 10};
    • cr_assert_eq(missingNumber(arr), 5);
    • }
    • Test(findMissingNumber, should_return_2_for_given_array) {
    • int arr[] = {1, 3, 4, 5};
    • int n = sizeof(arr) / sizeof(arr[0]);
    • cr_assert_eq(findMissingNumber(arr, n), 2);
    • std::vector<int> arr{0, 1, 3, 4, 5};
    • cr_assert_eq(missingNumber(arr), 2);
    • }