URAL 2024 Adventure Time 思维题、Interesting

A - Adventure Time
Time Limit:1000MS Memory Limit:65536KB 64bit IO Format:%I64d
& %I64u
Submit Status Practice URAL
2024

Description

‘Here’s for you!’ shouted Finn fighting the Shadow Guardians. ‘Jake! Collect the Darkness Rocks and let’s run from here!’

Jake would have been glad to finish as soon as possible, because it was wet and sad in the Dangerous Cave, but it was not so easy to
gather Rocks. So he called BMO and asked him to help with choosing an optimal set of Rocks. Jake told BMO that there were n Rocks
in the Cave, and they were numbered with different integers from 1 to n. Each Rock was painted one of 26 colors. Jake also reminded BMO of Princess Bubblegum’s warning: there should be at most k Rocks of
pairwise different colors among the Rocks taken from
the Cave. Only a set of Rocks with this property is safe. If one takes an unsafe set of Rocks from the Cave, Cosmic Evil will be awakened! Of course, Jake doesn’t want to awaken the Evil, but he wants to take
as many Darkness Rocks from the Cave as possible.
Help BMO to find the size of the largest safe set of Rocks and the number of different safe sets of this size. Two sets of Rocks are different if one of them contains a Rock with a number that is not contained in the other set.

Input

The first line contains n lowercase English letters (1 ≤ n ≤ 10 5); each letter denotes the color of a Rock. In the second line you are
given the integer k (1 ≤ k ≤ 26).

Output

Output two integers separated with a space: the size of the largest safe set of Darkness Rocks and the number of different safe sets of
this size.

Sample Input

input	output
abcde 1	1 5
ababac 2	5 1

Source

UESTC 2016 Summer Training #17 Div.2

URAL 2024

My Solution

统计每个字母出现的次数， 然后从大到小排序

最大的k的总个数就是 he size of the largest safe set of Darkness Rocks

然后1）如果color[k-1] != 0, 则 统计这k个里的 color[i] == color[k-1] 记为cnt1, 并统计所有的里面的color[i] == color[k-1] 记为 cnt2， 然后C[cnt2][cnt1]就是the number of different safe sets of this size.了

2）否则直接就是答案

复杂度 O(n)

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long LL;
const int maxn = 1e5 + 8;

char val[maxn];
LL color[26], C[maxn][30];

inline bool cmp(LL a, LL b)
{
return a > b;
}

int main()
{

memset(C, 0, sizeof C);
for(int i = 0; i <= 26; i++){
C[i][0] = 1;
for(int j = 1; j <= i; j++){
C[i][j] = C[i-1][j-1] + C[i-1][j];
}
}
#ifdef LOCAL
freopen("a.txt", "r", stdin);
//freopen("b.txt", "w", stdout);
int T = 3;
while(T--){
#endif // LOCAL
memset(color, 0, sizeof color);
LL sz = 0, num = 1, k;
scanf("%s", val);
scanf("%I64d", &k);
int len = strlen(val);

for(int i = 0; i < len; i++)
color[val[i] - 'a']++;

sort(color, color + 26, cmp);

int cnt1 = 0, cnt2 = 0;
for(int i = 0; i < k; i++){
sz += color[i];
if(color[k-1] !=0 && color[i] == color[k-1]) cnt1++;

}
for(int i = 0; i < 26; i++){
if(color[k-1] != 0 && color[i] == color[k-1]) cnt2++;
}
if(color[k-1] != 0){
num = C[cnt2][cnt1];
}
printf("%I64d %I64d", sz, num);
#ifdef LOCAL
printf("\n");
}
#endif // LOCAL
return 0;
}

Thank you!

------from ProLights