题目地址: https://leetcode.com/problems/two-sum/
题目描述:
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].
题目大意
给定一个整数数组 nums 和一个目标值 target,请你在该数组中找出和为目标值的那 两个 整数,并返回他们的数组下标。
你可以假设每种输入只会对应一个答案。但是,你不能重复利用这个数组中同样的元素。
解题方法
用空间换时间,先用Map把以前的数据存下来,再寻找存不存在,不存在就存入Map,存在直接返回结果(Accepted)
class Solution {
public int[] twoSum(int[] nums, int target) {
Map<Integer, Integer> map = new HashMap<>();
for (int i = 0; i < nums.length; i++) {
Integer temp = map.get(target - nums[i]);
if (temp == null) {
map.put(nums[i], i);
} else {
return new int[]{temp, i};
}
}
return new int[]{0, 0};
}
}
执行用时 内存消耗
2 ms 41.2 MB