class Solution { private long getSum(int[] chalk, int k) { long sum = 0; for (int uses : chalk) { sum += uses; if (sum > k) { break; } } return sum; } public int chalkReplacer(int[] chalk, int k) { var partialSum = getSum(chalk, k); // Remove whole iterations over the students k %= partialSum; for (int i = 0; i < chalk.length; ++i) { if (k < chalk[i]) { return i; } k -= chalk[i]; } return 0; } }