Codeforces Global Round 2 A. Ilya and a Colorful Walk(思维)

#include <bits/stdc++.h>
using namespace std;
int n;
map<int,int> ma1,ma2;

int main()
{
  scanf("%d",&n);
  for(int i=1;i<=n;i++){
    int x;
    scanf("%d",&x);
    if(ma1[x] == 0) ma1[x] = i;
    ma2[x] = i;
  }
  int ans = 0;
  for(int i=1;i<=n;i++){
    if(ma1[i] == ma2[i] && ma1[i] == 0) continue;
    if(ma1[i] == 1 && ma2[i] == n) continue;
    if(ma1[i] != 1 && ma2[i] != n){
      ans = max(ans, max(ma2[i] - 1, n - ma1[i]));
      continue;
    }
    if(ma1[i] == 1 || ma2[i] == n){
      ans = max(ans, n - 1);
      continue;
    }
  }
  printf("%d\n", ans);
  return 0;
}