CountConsecutiveOnes.java

/*https://leetcode.com/problems/number-of-substrings-with-only-1s/*/

class Solution {
   public int numSub(String s) {
        long consecutiveCount = 0, result = 0, mod = 1000000007;
        
        for (int i = 0; i < s.length(); ++i) {
            if (s.charAt(i) == '0')
            {
                result += ((consecutiveCount*(consecutiveCount+1))/2)%mod;
                result %= mod;
                consecutiveCount = 0;
            }
            else
            {
                ++consecutiveCount;
            }
        }
        if (s.charAt(s.length()-1) == '1')
        {
            result += ((consecutiveCount*(consecutiveCount+1))/2)%mod;
            result %= mod;
        }
        return (int)(result%mod);
    }
}

class Solution {
    public int numSub(String s) {
        char[] ch = s.toCharArray();
        long count =0;
        long result =0;
        for(int i=0; i<ch.length; i++)
        {
            if(ch[i] == '1')
            {
                count++;
                result += count;
            }
            else
                count = 0;
        }
        return (int)(result%1000000007);
    }
}