001 Two Sum

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/yexiguafu/article/details/73927612

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

public class Solution {
    public int[] twoSum(int[] numbers, int target) {
    int[] result = new int[2];
    Map<Integer, Integer> map = new HashMap<Integer, Integer>();
    for (int i = 0; i < numbers.length; i++) {
        if (map.containsKey(target - numbers[i])) {
            result[1] = i ;
            result[0] = map.get(target - numbers[i]);
            return result;
        }
        map.put(numbers[i], i );
    }
    return result;
}
}