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Maximizing array sum with given operation in C++

Narendra Kumar
Narendra Kumar
Updated on 11-Mar-2026 301 Views

DescriptionThere is an array of (2 * n – 1) integers. We can change sign of exactly n elements in the array. In other words, we can select exactly n array elements, and multiply each of them by -1. Find the maximum sum of the array.ExampleIf input array is {-2, 100, -3} then we can obtain maximum changing sign of -2 and -3. After changing sign array becomes −{2, 100, 3} and maximum sum of this array is 105.AlgorithmCount negative numbersCalculate the sum of the array by taking absolute values of the numbers.Find the minimum number of the array by ...

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Convert an array to reduced form (Using vector of pairs) in C++

Ayush Gupta
Ayush Gupta
Updated on 11-Mar-2026 291 Views

In this tutorial, we will be discussing a program to convert an array to its reduced form using vector of pairs.For this we will be provided with an array. Our task is to convert the given array in its reduced form such that it only contains elements ranging from 0 to n-1.Example#include using namespace std; //converting array to its reduced form void convert(int arr[], int n){    //creating a vector of pairs    vector v;    //putting elements in vector    //with their indexes    for (int i = 0; i < n; i++)       v.push_back(make_pair(arr[i], ...

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Element Appearing More Than 25% In Sorted Array in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 11-Mar-2026 386 Views

Suppose we have an array A. There are few elements. Some elements are common. We have to return an element that is appearing more than 25% spaces in the array. So if A = [1, 2, 4, 4, 4, 4, 5, 5, 6, 6, 7, 7], Here 4 has occurred four times. This is more than 25% of 12 (size of the array)To solve this, we will follow these steps −Read elements and store their respective frequenciesIf the frequency is greater than 25% of the array size, then return the result.ExampleLet us see the following implementation to get better understanding ...

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Ugly Number in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 11-Mar-2026 1K+ Views

Ugly numbers are those numbers whose prime factors are 2, 3 or 5. From 1 to 15, there are 11 ugly numbers 1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15. The numbers 7, 11, 13 are not ugly because they are prime. The number 14 is not ugly because in its prime factor the 7 will come. So suppose we want to check the 10th ugly number. The value will be 12.Let us see the following algorithm to get an idea −AlgorithmgetUglyNumbers(n)Input − The number of terms.Output − Find nth Ugly numbers.Begin    define array named uglyNum ...

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Maximizing the elements with a[i+1] > a[i] in C++

Narendra Kumar
Narendra Kumar
Updated on 11-Mar-2026 498 Views

Problem statementGiven an array of N integers, rearrange the array elements such that the next array element is greater than the previous element arr[i+1] > arr[i]ExampleIf input array is {300, 400, 400, 300} then rearranged array will be −{300, 400, 300, 400}. In this solution we get 2 indices with condition arr[i+1] > arr[i]. Hence answer is 2.AlgorithmIf all elements are distinct, then answer is simply n-1 where n is the number of elements in the arrayIf there are repeating elements, then answer is n – maxFrequencyExampleLet us now see an example −#include #define MAX 1000 using namespace std; ...

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Maximizing Unique Pairs from two arrays in C++

Narendra Kumar
Narendra Kumar
Updated on 11-Mar-2026 479 Views

Problem statementGiven two arrays of equal size N, form maximum number of pairs by using their elements, one from the first array and second from the second array, such that an element from each array is used at-most once and the absolute difference between the selected elements used for forming a pair is less than or equal to a given element K.ExampleIf input is −arr1[] = {3, 4, 5, 2, 1}arr2[] = {6, 5, 4, 7, 15}and k = 3 then we can form following 4 pairs whose absolute difference is less than or equal to 3 −(1, 4), (2, ...

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Replace Elements with Greatest Element on Right Side in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 11-Mar-2026 559 Views

Suppose we have an array A. We have to replace every element by the greatest element on the right side of this element. And replace the last one by -1. So if A = [5, 17, 40, 6, 3, 8, 2], then it will be [40,40,8,8,8,2,-1]To solve this, we will follow these steps −We will read the array element from right to left.take e := -1for i := n – 1 to 0temp := ee := max between e and array[i]array[i] := tempreturn arrayExampleLet us see the following implementation to get better understanding −#include using namespace std; void print_vector(vector v){    cout

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Maximum element in min heap in C++

Narendra Kumar
Narendra Kumar
Updated on 11-Mar-2026 463 Views

Problem statementGiven a minimum heap find maximum element in that.ExampleIf input heap is −Then maximum element is 55AlgorithmIn minimum heap parent node will be lesser than its children. Hence we can conclude that a non-leaf node cannot be the maximum.Search maximum element in the leaf nodesExampleLet us now see an example −#include using namespace std; int getMaxElement(int *heap, int n) {    int maxVal = heap[n / 2];    for (int i = n / 2 + 1; i < n; ++i) {       maxVal = max(maxVal, heap[i]);    }    return maxVal; } int main() {    int heap[] = {15, 27, 22, 35, 29, 55, 48}; int n = sizeof(heap) / sizeof(heap[0]);    cout

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Range Sum Query - Immutables in C++

Arnab Chakraborty
Arnab Chakraborty
Updated on 11-Mar-2026 305 Views

Suppose we have an array of integers. We have to find the sum of the elements present from index i to j. Two things we have to keep in mind that the array will be immutable, so elements will not be altered, and there will be multiple such queries. So we have to care about the execution time for a large number of queries. Suppose the array is like A = [5, 8, 3, 6, 1, 2, 5], then if query is (A, 0, 3), then it will be 5 + 8 + 3 + 6 = 22.To solve this, ...

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Convert array into Zig-Zag fashion in C++

Ayush Gupta
Ayush Gupta
Updated on 11-Mar-2026 469 Views

In this tutorial, we will be discussing a program to convert an array into zig-zag fashion.For this we will be provided with an array containing distinct elements. Our task is to rearrange the elements of the given array in a zig zag fashion with greater and smaller elements alternatively as compared to the previous element.Example#include using namespace std; //converting into zig-zag fashion void convert_zigzag(int arr[], int n) {    //flag denotes the greater or smaller relation    bool flag = true;    for (int i=0; i arr[i+1])          swap(arr[i], arr[i+1]);       } else { ...

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