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partition(index i, key key_j, int N) { // N is num reducers
 // find the data per reducer
 int dataPerRed = mC2 / N; // assuming m is known
 int prev_sum = 0;
 // calculate the total combinations contributed by previous indexes
 for (k=1; k < i; k++) {
  prev_sum += m - k + 1; // this adds the number of combinations contributed by kth index
 }
 prev_sum += j - i + 1 // self contribution
 return prev_sum % dataPerRed
}