| CSC300 / CSC402: XPerformanceOfArrays *1.1 [10/13] | |
01 |
public void push(double item) { if (N == a.length) resize((int)Math.ceil (N*1.1)); a[N] = item; N += 1; } |
Output
00 00 01 00 01 02 00 01 02 03 00 01 02 03 04 00 01 02 03 04 05 00 01 02 03 04 05 06 00 01 02 03 04 05 06 07 00 01 02 03 04 05 06 07 08 00 01 02 03 04 05 06 07 08 09 00 01 02 03 04 05 06 07 08 09 10 00 01 02 03 04 05 06 07 08 09 10 11 12 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Elapsed count f( 512): 5,721: 2.024 [ 0.001 : Infinity] Elapsed count f( 1,024): 11,402: 1.993 [ 0.001 : 1.000] Elapsed count f( 2,048): 22,520: 1.975 [ 0.002 : 2.000] Elapsed count f( 4,096): 48,320: 2.146 [ 0.001 : 0.500] Elapsed count f( 8,192): 94,698: 1.960 [ 0.002 : 2.000] Elapsed count f( 16,384): 185,318: 1.957 [ 0.005 : 2.500] Elapsed count f( 32,768): 362,372: 1.955 [ 0.006 : 1.200] Elapsed count f( 65,536): 772,598: 2.132 [ 0.012 : 2.000] Elapsed count f( 131,072): 1,509,413: 1.954 [ 0.018 : 1.500] Elapsed count f( 262,144): 2,948,653: 1.954 [ 0.018 : 1.000] Elapsed count f( 524,288): 6,283,714: 2.131 [ 0.048 : 2.667] Elapsed count f( 1,048,576): 12,272,649: 1.953 [ 0.046 : 0.958] Elapsed count f( 2,097,152): 23,970,316: 1.953 [ 0.051 : 1.109] Elapsed count f( 4,194,304): 46,819,577: 1.953 [ 0.102 : 2.000] Elapsed count f( 8,388,608): 99,760,500: 2.131 [ 0.223 : 2.186] Elapsed count f( 16,777,216): 194,835,921: 1.953 [ 0.454 : 2.036] Elapsed count f( 33,554,432): 380,541,255: 1.953 [ 0.953 : 2.099] Elapsed count f( 67,108,864): 743,288,834: 1.953 [ 1.579 : 1.657] Average delta: 2.002
N pushes in linear time
Each time we resize: constant pushes multiply by 1.1
Each push is amortized constant time
The choice of multiplier value is a tradeoff between time and space.