Partitioning in Quicksort How do we partition inplace
- Slides: 19
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n Q U I C K partition element S O R T I S C O O unpartitioned left partitioned right L 1
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me Q U I C K partition element S O R T I S C O O unpartitioned left partitioned right L 2
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me Q U I C K partition element S O R T I S C O O unpartitioned left partitioned right L 3
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me Q U I C K partition element S O R T I S C O O unpartitioned left partitioned right L 4
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me Q swap me U I C K partition element S O R T I S C O O unpartitioned left partitioned right L 5
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n C U I C K partition element S O R T I S Q O O unpartitioned left partitioned right L 6
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me C U I C K partition element S O R T I S Q O O unpartitioned left partitioned right L 7
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me C U I C K partition element S O R T I S Q O O unpartitioned left partitioned right L 8
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me C U I swap me C K partition element S O R T I S Q O O unpartitioned left partitioned right L 9
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 10
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 11
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 12
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 13
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 14
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 15
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 16
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap me C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 17
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n swap with partitioning element pointers cross C I I C K partition element S O R T U S Q O O unpartitioned left partitioned right L 18
Partitioning in Quicksort How do we partition in-place efficiently? Partition element = rightmost element. Scan from left for larger element. Scan from right for smaller element. Exchange. Repeat until pointers cross. n n n partition is complete C I I C K partition element L O R T U S Q O O unpartitioned left partitioned right S 19