JS solution for UniLecs task #140

get-unique-substr-lengths.js

const getNextState = (str, end) => {
  let i,
    start = str[0],
    substr = '',
    count = 1;

  for (i = 1; i < str.length; i++) {
    if (start === str[i]) {
      count++;
      if (end < i) {
        end = i - count;
      } else {
        end -= count;
      }
    } else {
      substr += str[i];
    }
  }

  if (count === 1) {
    end--;
  }

  return [substr, end, count];
};

const getUniqueSubstrLengths = str => {
  let end = 0,
    sum = 0,
    substr = str,
    result = [];

  while (substr.length) {
    if (substr.length === 1 && !sum) {
      result.push(1);
      break;
    }

    const [nextSubstr, nextEnd, count] = getNextState(substr, end);

    substr = nextSubstr;
    end = nextEnd;
    sum += count;

    if (!~end) {
      result.push(sum);
      end = 0;
      sum = 0;
    }
  }

  return result;
};