Count Pairs Summing to a Target

The array {1, 5, 7, -1, 5} is given. Read a target integer from standard input, then count how many index pairs (i, j) with i < j satisfy arr[i] + arr[j] == target, and print that count.

For example, if the input is 6, print the output shown in Expected Output.

The pairs summing to 6 are (1,5), (1,5), and (7,-1). Each unordered pair of positions is counted once.

Expected Output:

3↵

= newline. The output ends with a newline — print one after the last line.

Hints4 available

Topics:

Arrays

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