Summary Ranges

summaryRanges.js

/**
 * @param {number[]} nums
 * @return {string[]}
 */
var summaryRanges = function(nums) {
    let arr = [];
    let start  = nums[0];

    for(let i=0; i<nums.length; i++) {
        if(nums[i+1] - nums[i] == 1) continue;
        if(start == nums[i]) {
            arr.push(`${start}`);
            start = nums[i+1];
        }
        else {
            arr.push(`${start}->${nums[i]}`);
            start = nums[i+1];
        }
    }

    return arr;
};

// Keep a variable which stores the start value
// Loop through the array and check if the element ahead of the current one is 1 more than the current element
// If yes then move on normally and keep checking 
// If not, then check whether the current element is the same as the start element
// If yes, then simply push the start into the results array
// If not, then push "start->current element" into the results array
// Update the start position to the element ahead of the current element

// Time:O(n)
// Space: O(n)