LeetCode 1.两数之和【力扣——C/C++/Python三种编程语言题解】

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int* twoSum(int* nums, int numsSize, int target, int* returnSize){
    int i = 0, j = 0;
    int* ret = (int *)malloc(2 * sizeof(int));
    for(i = 0; i < numsSize; i++)
    {
        for(j = i + 1; j < numsSize; j++)
        {
            if((nums[i] + nums[j]) == target)
            {
                *ret = i;
                *(ret + 1) = j;
            }
        }
    }
    *returnSize = 2;
    return ret;
}

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int> m;
        int i = 0;
        do
        {
            unordered_map<int, int>::iterator it = m.find(target - nums[i]);
            if(it != m.end())
            {
                return {it->second, i};
            }
            else
            {
                m.insert(pair<int, int>(nums[i], i));
        i++;
            }
        }while(i < nums.size());
        return {};
    }
};

class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
        hashmap = {}
        for key, val in enumerate(nums):
            if target - val in hashmap:
                return [key, hashmap[target - val]]
            hashmap[val] = key