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].
Map作为寄存器，避免多次循环
class Solution {
public int[] twoSum(int[] nums, int target) {
Map<Integer,Integer> dataMap = new HashMap<>();
for(int i = 0; i < nums.length; i++){
int remainder = target - nums[i];
if(dataMap.containsKey(remainder)){
return new int[]{dataMap.get(remainder), i};
}
dataMap.put(nums[i],i);
}
return null;
}
}
