leetcode

Two Sum

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.

Example:

Given nums = [2, 7, 11, 15], target = 9,Because nums[0] + nums[1] = 2 + 7 = 9,return [0, 1].

Solution:

public int[] twoSum(int[] nums, int target) {    Map<Integer, Integer> map = new HashMap<>();    for (int i = 0; i < nums.length; i++) {        int num = target - nums[i];        if (map.containsKey(num)) {            return new int[] { map.get(num), i };        }        map.put(nums[i], i);    }    throw new RuntimeException("没有对应的两个数");}