https://leetcode.com/problems/x-of-a-kind-in-a-deck-of-cards/
In a deck of cards, each card has an integer written on it.
Return true if and only if you can choose X >= 2 such that it is possible to split the entire deck into 1 or more groups of cards, where:
- Each group has exactly
Xcards. - All the cards in each group have the same integer.
Example 1:
Input: [1,2,3,4,4,3,2,1]
Output: true
Explanation: Possible partition [1,1],[2,2],[3,3],[4,4]
Example 2:
Input: [1,1,1,2,2,2,3,3]
Output: false
Explanation: No possible partition.
Example 3:
Input: [1]
Output: false
Explanation: No possible partition.
Example 4:
Input: [1,1]
Output: true
Explanation: Possible partition [1,1]
Example 5:
Input: [1,1,2,2,2,2] Output: true Explanation: Possible partition [1,1],[2,2],[2,2]
class Solution {
public:
int hasGroupsSizeX(vector<int>& deck) {
int len = deck.size();
int num[10010];
memset(num, 0, sizeof(num));
if(len < 2) return false;
for(int i = 0; i < len; i ++) num[deck[i]] ++;
int ans = 0;
for(int i = 0; i < 10010; i ++) {
if(num[i]) ans = gcd(ans, num[i]);
}
return ans > 1;
}
int gcd(int a, int b) {
return a == 0 ? b : gcd(b % a, a);
}
};