You are given n strings s1, s2, ..., sn. Each of these strings consists only of letters 'a' and 'b', and the length of each string can be at most 2. In other words, the only allowed strings are "a", "b", "aa", "ab", "ba" and "bb".
Consider a permutation p = {p1, p2, ..., pn} of the integers {1, 2, ..., n}. Using this permutation, you can obtain a new string S = sp1+ sp2 + ... + spn, where the operator + denotes concatenation of strings.
You can shorten the string S by performing the following operation any number of times: choose two consecutive equal characters and remove one of these characters from the string. For example, the string "aabb" can be shortened to "abb" or "aab" in one operation, and then optionally it could still be shortened to "ab".
You are allowed to choose any permutation p. Take the string Sobtained using this permutation, and using any sequence of operations, minimize the string length. Find the minimum possible length of the string obtainable.
Input
The first line of the input contains an integer T denoting the number of test cases. The description of T test cases follows.
The first line of each test case contains an integer n.
The second line of each test case contains n space-separated strings s1, s2, ..., sn.
Output
For each test case, output a single line containing one integer corresponding to the minimum possible length of the shortened string.
Constraints
- 1 ≤ T ≤ 105
- 1 ≤ n ≤ 105
- sum of n over all test cases won't exceed 106
Example
Input 2 2 ba ab 4 a b a b Output 3 2
Explanation
Testcase 1:
You can consider the permutation (2, 1). Using this, you get the string S = sp1 + sp2 = ab + ba = abba. You can then take the two adjacent b's and remove one of them to get aba, whose length is 3. You cannot do any better, and hence the answer is 3.
Testcase 2:
You can consider the permutation (1, 3, 2, 4). Using this, you get the string S = sp1 + sp3 + sp2 + sp4 = a + a + b + b = aabb. You can then take the two adjacent b's and remove one of them to get aab. Then you can take the two adjacent a's and remove one of them to get ab. We end up with a length of 2, and you cannot do any better. Hence the answer is 2.
#include <iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int main()
{
int t;
scanf("%d",&t);
while(t--)
{
int n;
scanf("%d",&n);
char s[3];
int a,b,c,d;
a=b=c=d=0;
for(int i=0; i<n; i++)
{
scanf("%s",s);
if(strcmp(s,"a")==0||strcmp(s,"aa")==0)
a++;
else if(strcmp(s,"b")==0||strcmp(s,"bb")==0)
b++;
else if(strcmp(s,"ab")==0)
c++;
else d++;
}
int ans=0;
if(b!=0)
b=1;
if(a!=0)
a=1;
if(d!=0||c!=0)
{
a=b=0;
if(c>d)
ans=c*2;
else if(d>c)
ans=d*2;
else ans=d*2+1;
}
else ans=a+b;
printf("%d\n",ans);
}
return 0;
}
本文探讨了一种通过优化字符串操作来最小化最终字符串长度的算法。通过对一系列仅包含'a'和'b'的字符串进行排列组合,并允许删除相邻重复字符,算法寻找最短可能的字符串长度。案例分析展示了如何通过特定的字符串排列实现长度最小化。
591

被折叠的 条评论
为什么被折叠?



