【★】两数之和 II - 输入有序数组 twoSum

解法思路：使用Java双指针 ，两个指针从头部和尾部向中间移动,找到就记录下来。

代码如下：

//Answer1：Java双指针
class Solution {
    public int[] twoSum(int[] numbers, int target) {
        int[] ans = new int[2];
        int len = numbers.length;
        int left = 0, right = len - 1;
        while (left < right) {
            int sum = numbers[left] + numbers[right];
            if (sum < target) {
                left++;
            } else if (sum > target) {
                right--;
            } else {
                ans[0] = left + 1;
                ans[1] = right + 1;
                return ans;
            }
        }
        return ans;
    }
}

解法思路：哈希表

代码如下：

//Answer2：哈希表
lass Solution {
    public int[] twoSum(int[] numbers, int target) {
        int[] ans = new int[2];
        int len = numbers.length;
        Map map = new HashMap<>();
        for (int i = 0; i < len; i++) {
            map.put(numbers[i], i + 1);
        }
        for (int i = 0; i < len; i++) {
            int need = target - numbers[i];
            if (map.containsKey(need)) {
                ans[0] = i + 1;
                ans[1] = map.get(need);
                return ans;
            }
        }
        return ans;
    }
}

运行结果截图如下：