【leetcode刷题】20T1-两数之和

示例:
给定 nums = [2, 7, 11, 15], target = 9
因为 nums[0] + nums[1] = 2 + 7 = 9
所以返回 [0, 1]

class Solution(object):
    def twoSum(self, nums, target):
        """
        :type nums: List[int]
        :type target: int
        :rtype: List[int]
        """
        # 特殊情况
        half = target // 2
        if nums.count(half) == 2 and half * 2 == target:
            return [nums.index(half), len(nums) - 1 - nums[::-1].index(half)]

        # hash
        d = {}
        for i, n in enumerate(nums):
            d[n] = i

        # 遍历
        for i, n in enumerate(nums):
            if n == target - n:
                continue
            if (target - n) in d:
                return [i, d[target - n]]

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        // 暴力
        vector<int> res;
        for (int i=0; i<nums.size(); i++){
            for (int j=i+1; j<nums.size(); j++){
                if (nums[i] + nums[j] == target){
                    res.push_back(i);
                    res.push_back(j);
                }
            }
        }
        return res;
    }
};