TwoSum.java

package easy;

import java.util.Arrays;

/**
 * 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.
 * <p>
 * 给定一个整数数组和一个目标值，找出数组中和为目标值的两个数的数组下标。
 * 你可以假设每个输入只对应一种答案，且同样的元素不能被重复利用。
 * <p>
 * Created by Kaming on 2018/7/12.
 */
public class TwoSum {

    /**
     * Example:
     * <p>
     * Given nums = [2, 7, 11, 15], target = 9
     * <p>
     * Because nums[0] + nums[1] = 2 + 7 = 9
     * return [0, 1]
     */
    public static void main(String[] args) {
        int[] sum = twoSum(new int[]{2, 7, 11, 15}, 9);
        System.out.print(Arrays.toString(sum));
    }

    private static int[] twoSum(int[] nums, int target) {
        int[] sum = null;
        for (int i = 0; i < nums.length - 1; i++) {
            for (int j = i + 1; j < nums.length; j++) {
                if (nums[i] + nums[j] == target) {
                    sum = new int[]{i, j};
                    break;
                }
            }
            if (sum != null) {
                break;
            }
        }
        return sum;
    }

}