Find a Pair With Given Sum

Unsorted Array

Input: arr[] = {2, 5, 13, 6, 9, 4}, sum=10
Output: Yes

Input: arr[] = {10, 5, 13, 6, 9, 4}, sum=5
Output: No

Implementation

package main

import (
    "fmt"
    "sort"
)

func main() {
    arr := []int{2, 5, 13, 6, 9, 10}
    k := 13
    res := findPairWithGivenSum(arr, k)
    fmt.Println(res)

}

func findPairWithGivenSum(arr []int, target int) bool {
    m := make(map[int]bool)
    for _, ele := range arr {
        if _, ok := m[target-ele]; ok {
            return true
        }
        m[ele] = true
    }
    return false
}

Sorted Array

Input: arr[] = {2, 4, 6, 9, 12, 13}, sum=10
Output: Yes

Input: arr[] = {3, 4, 6, 9, 10, 13}, sum=8
Output: No

Implementation

package main

import (
    "fmt"
    "sort"
)

func main() {
    arr := []int{2, 5, 13, 6, 9, 10}
    k := 13
    res := findPairWithGivenSum(arr, k)
    fmt.Println(res)

}

func findPairWithGivenSum(arr []int, target int) bool {
    i := 0
    j := len(arr) - 1
    for i < j {
        sum := arr[i] + arr[j]
        if sum == target {
            return true
        } else if sum > target {
            j--
        } else {
            i++
        }
    }
    return false
}