使用javascript从数组中获取值等于特定和的元素对

function findPairsWithSum(arr, targetSum) {
    const pairs = [];
    for (let i = 0; i < arr.length; i++) {
        for (let j = i + 1; j < arr.length; j++) {
            if (arr[i] + arr[j] === targetSum) {
                pairs.push([arr[i], arr[j]]);
            }
        }
    }
    return pairs;
}

// 示例用法
const arr = [1, 2, 3, 4, 5];
const targetSum = 5;
console.log(findPairsWithSum(arr, targetSum)); // 输出: [[1, 4], [2, 3]]

function findPairsWithSum(arr, targetSum) {
    const pairs = [];
    const seen = new Set();
    for (let num of arr) {
        const complement = targetSum - num;
        if (seen.has(complement)) {
            pairs.push([complement, num]);
        }
        seen.add(num);
    }
    return pairs;
}

// 示例用法
const arr = [1, 2, 3, 4, 5];
const targetSum = 5;
console.log(findPairsWithSum(arr, targetSum)); // 输出: [[1, 4], [2, 3]]

function findPairsWithSum(arr, targetSum) {
    const pairs = [];
    let left = 0;
    let right = arr.length - 1;
    while (left < right) {
        const sum = arr[left] + arr[right];
        if (sum === targetSum) {
            pairs.push([arr[left], arr[right]]);
            left++;
            right--;
        } else if (sum < targetSum) {
            left++;
        } else {
            right--;
        }
    }
    return pairs;
}

// 示例用法
const arr = [1, 2, 3, 4, 5];
const targetSum = 5;
console.log(findPairsWithSum(arr, targetSum)); // 输出: [[1, 4], [2, 3]]