思路：寻找区间内只有1种奶牛或者2种奶牛数量相等的最长区间，将两种奶奶记作1，-1数量相等则区间和为0

代码：

#include <iostream>
#include <cstring>
#include <algorithm>
#include <unordered_map>#define x first
#define y secondusing namespace std;
const int N = 100010;
typedef pair<int, int> PII;PII q[N];int main()
{int n;scanf("%d", &n);for(int i=1;i<=n;i++){int x;char str[2];scanf("%d%s", &x, str);if(*str=='G') q[i]={x,1};else q[i]={x,-1};}sort(q+1,q+1+n);unordered_map<int,int> hash;int res=0,sum=0,last;for(int i=1;i<=n;i++){if(!hash.count(sum)) hash[sum]=q[i].x;sum+=q[i].y;if(hash.count(sum)) res=max(res,q[i].x-hash[sum]);if(i==1||q[i].y!=q[i-1].y) last=q[i].x;res=max(res,q[i].x-last);}printf("%d",res);return 0;
}