Notes

public static int[] climbingLeaderboard(int[] ranked, int[] player)
{
// Determine the unique, descending list of scores on the leaderboard.
int[] distinctScores = ranked.Distinct().OrderByDescending(x => x).ToArray();

int[] playerRanks = new int[player.Length];
int currentPlayerIndex = 0;
int currentRank = 1;

// Compare each player's score to the distinct scores on the leaderboard
// and determine their rank.
for (int i = 0; i < distinctScores.Length && currentPlayerIndex < player.Length; i++)
{
if (distinctScores[i] > player[currentPlayerIndex])
{
// If the current player's score is less than the current distinct score,
// they have a higher rank than the current rank.
currentRank++;
}
else if (distinctScores[i] == player[currentPlayerIndex])
{
// If the current player's score is equal to the current distinct score,
// they have the same rank as the current rank.
playerRanks[currentPlayerIndex] = currentRank;
currentPlayerIndex++;

// Don't increment the rank, since the next player may have the same score.
i--;
}
else
{
// If the current player's score is greater than the current distinct score,
// they have a lower rank than the current rank.
playerRanks[currentPlayerIndex] = currentRank;
currentPlayerIndex++;
}
}

// If there are remaining players, assign them the lowest rank.
while (currentPlayerIndex < player.Length)
{
playerRanks[currentPlayerIndex] = currentRank;
currentPlayerIndex++;
}

return playerRanks;
}