Array Summary

Array

1.  Two Sum     Hash table (map<int, int> hashMap; // first is the value, second is the index),f
                         find(target - numbers[i]);

167  Two Sum II - Input array is sorted  
// Utilize the fact that the array is sorted, sum from both left and right side.
// If the summation is too large, decrease the high index, else if the summation
// is too low, increase the low index. else if the summation is the target value,
// create the vector<int> and return the vector<int>({low + 1, hight + 1})

170. Two Sum III - Data structure design
         Solution:  Two Sum III

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