# Find the smallest contiguous sum pair in an Array

Given an array arr[] containing N distinct integers, the task is to find a contiguous pair such that sum of both elements in pair is minimum.
Examples:

Input: arr[] = {1, 2, 3, 4}
Output: (1, 2)
Explanation:
Here, contiguous pairs with their sum are (1, 2) = 3, (2, 3) = 5, (3, 4) = 7 and minimum is 3.
Input: arr[] = {4, 9, -3, 2, 0}
Output: (-3, 2)
Explanation:
Here, contiguous pairs with their sum are (4, 9) = 13, (9, -3) = 6, (-3, 2) = -1, (2, 0) = 2

Approach:
To solve the problem mentioned above we have to consider all the contiguous pairs and find their sum. The pair having the smallest(minimum) sum is the required answer.
Below is the implementation of above approach:

## C++

 `//C++ program to find the smallest` `// sum contiguous pair` `#include` `using` `namespace` `std;` ` `  `// Function to find the smallest sum` `// contiguous pair` `vector<``int``> smallestSumpair(``int` `arr[], ``int` `n)` `{`   `    ``// Contiguous pair` `    ``vector<``int``>pair;`   `    ``// isntialize minimum sum` `    ``// with maximum value` `    ``int` `min_sum = INT_MAX;`   `    ``for``(``int` `i = 1; i < n; i++)` `    ``{`   `        ``// Checking for minimum value` `        ``if``( min_sum > (arr[i] + arr[i - 1]))` `        ``{` `            ``min_sum = arr[i] + arr[i - 1];` `            ``if` `(pair.empty())` `            ``{`   `                ``// Add to pair` `                ``pair.push_back(arr[i - 1]);` `                ``pair.push_back(arr[i]);` `            ``}` `            ``else` `            ``{`   `                ``// Updating pair` `                ``pair = arr[i - 1];` `                ``pair = arr[i];` `            ``}` `        ``}` `    ``}` `    ``return` `pair;` `}` ` `  `// Driver code` `int` `main()` `{` `   ``int` `arr[] = {4, 9, -3, 2, 0};` `   ``int` `n = ``sizeof``(arr) / ``sizeof``(arr);` `  `  `   ``vector<``int``>pair = smallestSumpair(arr, n);` `   ``cout << pair << ``" "` `<< pair;` `}`   `// This code is contributed by chitranayal`

## Python3

 `# Python program to find the smallest` `# sum contiguous pair`   `# importing sys` `import` `sys`   `# Function to find the smallest sum` `# contiguous pair`     `def` `smallestSumpair(arr, n):`   `    ``# Contiguous pair` `    ``pair ``=` `[]`   `    ``# isntialize minimum sum` `    ``# with maximum value` `    ``min_sum ``=` `sys.maxsize`   `    ``for` `i ``in` `range``(``1``, n):`   `        ``# checking for minimum value` `        ``if` `min_sum > (arr[i] ``+` `arr[i``-``1``]):` `            ``min_sum ``=` `arr[i] ``+` `arr[i``-``1``]`   `            ``if` `pair ``=``=` `[]:`   `                ``# Add to pair` `                ``pair.append(arr[i``-``1``])` `                ``pair.append(arr[i])` `            ``else``:`   `                ``# Updating pair` `                ``pair[``0``] ``=` `arr[i``-``1``]` `                ``pair[``1``] ``=` `arr[i]`   `    ``return` `pair`     `# Driver code` `arr ``=` `[``4``, ``9``, ``-``3``, ``2``, ``0``]` `n ``=` `len``(arr)` `pair ``=` `smallestSumpair(arr, n)` `print``(pair[``0``], pair[``1``])`

Output

```-3 2

```

Time Complexity: O(n)

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Improved By : chitranayal

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