双指针法,结果只能从最左边或者最右边或者最左边加上最右边中取
class Solution { public: int findLengthOfShortestSubarray(vector<int>& arr) { int n = arr.size(),res = 1,res2 = 1,res3 = 1,p = n-1,q = 0; for(int i=1;i<n;i++){ if(arr[i]<arr[i-1]){ p = i-1; break; } } if(p==n-1)return 0; for(int i=n-1;i>0;i--){ if(arr[i]<arr[i-1]){ q = i; break; } } int i = 0,j = q; while(i<=p&&j<=n-1){ if(arr[i]<=arr[j]){ res = max(res,i+1+n-j); i++; }else{ j++; } } res3 = n-res; res = n-(p+1); res2 = n-(n-q); return min(min(res,res2),res3); } };