letecode [167] - Two Sum II - Input array is sorted

 Given an array of integers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2.

Note:

• Your returned answers (both index1 and index2) are not zero-based.
• You may assume that each input would have exactly one solution and you may not use the same element twice.

Example:

Input: numbers = [2,7,11,15], target = 9
Output: [1,2]
Explanation: The sum of 2 and 7 is 9. Therefore index1 = 1, index2 = 2.

题目大意：

 　　给定一个数组和目标值，找到数组中两数之和等于目标值。返回两数的下标（小在前）。

理  解：

 　　遍历数组，利用map存放元素，若target-nums[i]在map中则找到这两个元素；否则将当期元素nums[i]放入map中。

代 码 C++：

class Solution {
public:
    vector<int> twoSum(vector<int>& numbers, int target) {
        int n = numbers.size();
        int i;
        map<int,int> m;
        vector<int> res;
        map<int,int>::iterator it;
        for(i=0;i<n;++i){
            if(target>0 && numbers[i]>target)
                break;
            it = m.find(target-numbers[i]);
            if(it!=m.end()){
                res.push_back(it->second+1);
                res.push_back(i+1);
                return res;
            }
            m.insert(pair(numbers[i],i));
             
        }
        return res;
    }
};

运行结果：

 　　执行用时 :12 ms, 在所有C++提交中击败了84.11%的用户

标签：map,return,target,res,Sum,Two,letecode,vector,numbers
来源： https://www.cnblogs.com/lpomeloz/p/11002953.html