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C++ program to find length of non empty substring whose sum is even
Suppose we have an array A with n elements. We have to find the length of a non-empty subset of its elements such that their sum is even or return -1 when there is no such subset.
So, if the input is like A = [1, 3, 7], then the output will be 2, because sum of [1, 3] is 4.
Steps
To solve this, we will follow these steps −
n := size of A for initialize i := 0, when i < n, update (increase i by 1), do: if A[i] mod 2 is same as 0, then: k := i + 1 if n is 1 AND k is 0, then: return -1 otherwise when k is not equal to 0, then: return 1 Otherwise return 2
Example
Let us see the following implementation to get better understanding −
#include <bits/stdc++.h>
using namespace std;
int solve(vector<int> A) {
long n = A.size(), k = 0;
for (long i = 0; i < n; i++) {
if (A[i] % 2 == 0) {
k = i + 1;
}
}
if (n == 1 & k == 0) {
return -1;
}
else if (k != 0) {
return 1;
} else {
return 2;
}
}
int main() {
vector<int> A = { 1, 3, 7 };
cout << solve(A) << endl;
}Input
{ 1, 3, 7 }Output
2
Updated on: 04-Mar-2022
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