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  • 【LeetCode】001. Two Sum

    题目:

    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 sameelement twice.

    Example:

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

    题解:

    Solution 1 (my submmision)

    class Solution {
    public:
        vector<int> twoSum(vector<int>& nums, int target) {
            vector<int> res;
            unordered_map<int, int> map;
            for(int i = 0; i < nums.size(); ++i){
                int val = target - nums[i];
                if(map.find(val) != map.end()){
                    res.push_back(map[val]);
                    map[nums[i]] = i;
                    res.push_back(map[nums[i]]);
                    break;
                }
                map[nums[i]] = i;
            }
            return res;
        }
    };

    Solution 2

    class Solution {
    public:
        vector<int> twoSum(vector<int>& nums, int target) {
            vector<int> res;
            unordered_map<int, int> map;
            for(int i = 0; i < nums.size(); ++i){
                if(map.find(nums[i]) == map.end()){
                    map[target - nums[i]] = i;
                } else {
                    res.push_back(map[nums[i]]);
                    res.push_back(i);
                    break;
                }
            }
            return res;
        }
    };

    相当于建立数组中每个元素的相对应的加数的集合,这个加数对应了原数组中元素的坐标。

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  • 原文地址:https://www.cnblogs.com/Atanisi/p/7467951.html
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