Number of Ways to Split a String.java

class Solution {
    public int numWays(String s) {
        long n=s.length();
        long one=0;//to count number of ones
        long mod=1_000_000_007;
        char[] c=s.toCharArray();
        for(int i=0;i<c.length;i++)
        {
            if(c[i]=='1')
                one++;
        }
        
             //there will be 3 cases
            // 1.no ones present in the string
            // 2.number of ones present in the string isnt divisible by 3(since we need to cut 3 parts)
            // 3.number of ones divisible by 3
        
        if(one==0)//case 1
        {
            return (int)((((n-1)*(n-2))/2)%mod);
        }
        if(one%3!=0)//case 2,which means we cant split ones equally
            return 0;
        //case 3
        long ones=one/3;//number of ones that should be present in each part
        one=0;
        long part1=0;//number of ways in which part1 and part2 can be split
        long part2=0;
        for(int i=0;i<c.length;i++)
        {
            if(c[i]=='1')
                one++;
            if(one==ones)
                part1++;
            if(one==2*ones)
                part2++;
        }
        
        return (int)((part1*part2)%mod);
    }
}