Leetcode Kth largest Element in an Array (quick sort)

Test instructions

What is the number of K-large in an unordered array?

Ideas:

According to the idea of the fast line, if each time divided into two paragraphs, set to L and R. If r>=k, the answer is set on the right, otherwise the left collection.

The 3-bit method is used here. Pay attention to the fast-line and write the dead loop.

1 classSolution {2  Public:3     intFindkthlargest (vector<int>& Nums,intk) {4         if(K>nums.size ())return 0;5            returnDFS (Nums,0, Nums.size ()-1, k);6     }7 8     intDFS (vector<int>& Nums,intSintEintk)9     {Ten         intL=s, r=e; One         //three-bit take-in method A         if(nums[e]>Nums[s]) swap (nums[s],nums[e]);  -         if(nums[s]>nums[(s+e)/2]) Swap (nums[s],nums[(s+e)/2]);  -  the         intMid=Nums[s]; -          while(l<R) -         { -              while(L<r && Nums[r]>=mid) r--;//Find Small +nums[l]=Nums[r]; -              while(L<r && Nums[l]<=mid) l++;//looking for big +nums[r]=Nums[l]; A         } atnums[l]=mid; -         intLen=e-l;//number of elements in the right part -         if(len+1==K)returnmid; -         if(len>=k)returnDFS (nums,l+1, e,k); -         Else        returnDFS (nums,s,l-1, k-len-1); -     } in};

AC Code

Quick line:

1     voidQuick (vector<int>& Nums,intSinte)2     {3         intL=s, r=e;4         //three-bit take-in method5         if(Nums[e]>nums[s]) swap (nums[s],nums[e]);//ask for Big6         if(nums[s]>nums[(s+e)/2]) Swap (nums[s],nums[(s+e)/2]);//in Demand7         intpivot=Nums[s];8          while(l<R)9         {Ten              while(L<r && Nums[r]>=pivot) r--;//Find Small Onenums[l]=Nums[r]; A  -              while(L<r && Nums[l]<=pivot) l++;//looking for big -nums[r]=Nums[l]; the         } -nums[l]=pivot; -Quick (nums,s,l-1); -Quick (nums,l+1, e); +}

AC Code

Leetcode Kth largest Element in an Array (quick sort)