Formatted question description: https://leetcode.ca/all/1399.html

1399. Count Largest Group (Easy)

Given an integer n. Each number from 1 to n is grouped according to the sum of its digits.

Return how many groups have the largest size.

Example 1:

Input: n = 13
Output: 4
Explanation: There are 9 groups in total, they are grouped according sum of its digits of numbers from 1 to 13:
[1,10], [2,11], [3,12], [4,13], [5], [6], [7], [8], [9]. There are 4 groups with largest size.

Example 2:

Input: n = 2
Output: 2
Explanation: There are 2 groups [1], [2] of size 1.

Example 3:

Input: n = 15
Output: 6

Example 4:

Input: n = 24
Output: 5

Constraints:

1 <= n <= 10^4

Related Topics:
Array

Solution 1.

class Solution {
    public int countLargestGroup(int n) {
        int maxCount = 0;
        Map<Integer, Integer> map = new HashMap<Integer, Integer>();
        for (int i = 1; i <= n; i++) {
            int sum = sumDigits(i);
            int count = map.getOrDefault(sum, 0) + 1;
            map.put(sum, count);
            maxCount = Math.max(maxCount, count);
        }
        int groups = 0;
        Set<Integer> keySet = map.keySet();
        for (int key : keySet) {
            if (map.get(key) == maxCount)
                groups++;
        }
        return groups;
    }

    public int sumDigits(int num) {
        char[] array = String.valueOf(num).toCharArray();
        int sum = 0;
        for (char c : array)
            sum += c - '0';
        return sum;
    }
}

############

class Solution {
    public int countLargestGroup(int n) {
        int[] cnt = new int[40];
        int mx = 0, ans = 0;
        for (int i = 1; i <= n; ++i) {
            int t = 0;
            int j = i;
            while (j != 0) {
                t += j % 10;
                j /= 10;
            }
            ++cnt[t];
            if (mx < cnt[t]) {
                mx = cnt[t];
                ans = 1;
            } else if (mx == cnt[t]) {
                ++ans;
            }
        }
        return ans;
    }
}

// OJ: https://leetcode.com/problems/count-largest-group/
// Time: O(N)
// Space: O(N)
class Solution {
public:
    int countLargestGroup(int n) {
        unordered_map<int, int> m;
        for (int i = 1; i <= n; ++i) {
            int sum = 0, x = i;
            while (x) {
                sum += x % 10;
                x /= 10;
            }
            m[sum]++;
        }
        int maxSize = 0;
        for (auto &p : m) {
            maxSize = max(maxSize, p.second);
        }
        int ans = 0;
        for (auto &p : m) {
            if (p.second == maxSize) ++ans;
        }
        return ans;
    }
};

class Solution:
    def countLargestGroup(self, n: int) -> int:
        cnt = Counter()
        ans, mx = 0, 0
        for i in range(1, n + 1):
            t = sum(int(v) for v in str(i))
            cnt[t] += 1
            if mx < cnt[t]:
                mx = cnt[t]
                ans = 1
            elif mx == cnt[t]:
                ans += 1
        return ans

func countLargestGroup(n int) int {
	cnt := make([]int, 40)
	mx, ans := 0, 0
	for i := 1; i <= n; i++ {
		t := 0
		j := i
		for j != 0 {
			t += j % 10
			j /= 10
		}
		cnt[t]++
		if mx < cnt[t] {
			mx = cnt[t]
			ans = 1
		} else if mx == cnt[t] {
			ans++
		}
	}
	return ans
}

function countLargestGroup(n: number): number {
    const cnt: number[] = new Array(40).fill(0);
    let mx = 0;
    let ans = 0;
    for (let i = 1; i <= n; ++i) {
        let s = 0;
        for (let x = i; x; x = Math.floor(x / 10)) {
            s += x % 10;
        }
        ++cnt[s];
        if (mx < cnt[s]) {
            mx = cnt[s];
            ans = 1;
        } else if (mx === cnt[s]) {
            ++ans;
        }
    }
    return ans;
}

1399 - Count Largest Group

1399. Count Largest Group (Easy)

Solution 1.

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1399. Count Largest Group (Easy)

Solution 1.

All Problems

All Solutions