Two Sum

/**

* @param {number[]} nums

* @param {number} target

* @return {number[]}

*/

const twoSum = function (nums, target) {

/**

* remain value is the final value of target and array's individual element subtraction.

* If remain Value is present in the given nums array that means we have our answer

* start and current represents the index value of subtracted number and current number against which comparision is happening in loop;

* result is to store final result and retuen it ;

*/

let start = 0;

let remain = target - nums[start];

let current = 1;

let result = [];

/**

* WHY NOT FOR LOOP?

* For loop will only run for limited number of time based on the emenent size in the array, but here i need to loop against every index to compare it with remain value

* and update remain value till the last element , while is more suitable for such problems where we don't have any predefined iteration count. while loop totally depends

* on base condition

*/

/**

* This condition will make sure we consider all the array elements as substration value.

*/

while (start <= nums.length - 1) {

// O(n) - NOt sure here!!!

if (remain === nums[current]) {

if (start !== current) {

result = [start, current];

console.log(result);

break;

}

}

if (current === nums.length - 1) {

/**

* I increment current value on every iteration and start value once in loop single phase.

* after one loop cycle assign current to 0 index again ;

*/

current = 0;

start++;

remain = target - nums[start];

}

current++;

}

return result;

};

twoSum([3, 2, 4], 6);