contest 78 LC

P1 ----https://leetcode.com/contest/biweekly-contest-78/problems/number-of-ways-to-split-array/

class Solution {
public:
    
    //store total sum of nums in right_sum and iterate over nums
    //add nums[i] in left sum and subtract nums[i] from right sum
    //when condition match increase valid_split by 1.
    int waysToSplitArray(vector<int>& nums) 
    {
        int valid_split=0;
        long long right_sum=0, left_sum=0;
        
        //store total sum of nums in right_sum
        for(int i=0; i<nums.size(); i++) total_sum += nums[i];
        
        for(int i=0; i<nums.size()-1; i++)
        {
            left_sum += nums[i]; //add nums[i] in left sum 
           total_sum -= nums[i]; // and subtract nums[i] from right sum
            
            //check whether left_sum is greater than or equal to right_sum
            //and increase the valid_split by 1
            if(left_sum >= total_sum) 
                valid_split++; 
        }
        return valid_split;
        
    }
};
https://leetcode.com/contest/biweekly-contest-78/problems/find-the-k-beauty-of-a-number/

class Solution {
public:
    int divisorSubstrings(int num, int k) {
        string str = to_string(num);
        int i = 0, j = 0, n = str.length();
        int ind = 0;
        
        while(j < n)
        {
            if(j - i + 1 < k)
            {
			// increment j till we get the window size
                ++j;
            }
            else if(j - i + 1 == k)
            {
			// on hiting the window size
			// extract window string and convert to int
			// check if it follows the given condition
                string s = str.substr(i,k);                               ///for python string s = str.substr(i,i+k);  
                int n = stoi(s);
                if(n != 0 && num % n == 0 )
                    ++ind;
                
				// shift the window by ++j;
				// remove previous calculation by ++i
                ++i;
                ++j;
            }
                
        }
        
        return ind;
    }
};