leetcode-1-数组题-两数之和

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题目

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解法

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class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        if (nums.size() <= 0)
            return {-1, -1};
        
        unordered_map<int, unsigned int> value_pos;
        
        for(unsigned int i = 0; i < nums.size(); ++i){    // O(n)
            if (value_pos.count(target - nums[i]) > 0){
                return {value_pos[target-nums[i]], i};
            }
            value_pos[nums[i]] = i;
        }
        
        return {-1, -1};
    }
};