| CSC300 / CSC402: XPerformanceOfArrays *2 [6/13] | |
01 |
public void push(double item) { if (N == a.length) resize(2*N); a[N] = item; N += 1; } |
Output
00 00 01 00 01 02 03 00 01 02 03 04 05 06 07 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 Elapsed count f( 512): 1,023: 2.002 [ 0.000 : NaN] Elapsed count f( 1,024): 2,047: 2.001 [ 0.000 : NaN] Elapsed count f( 2,048): 4,095: 2.000 [ 0.000 : NaN] Elapsed count f( 4,096): 8,191: 2.000 [ 0.000 : NaN] Elapsed count f( 8,192): 16,383: 2.000 [ 0.000 : NaN] Elapsed count f( 16,384): 32,767: 2.000 [ 0.001 : Infinity] Elapsed count f( 32,768): 65,535: 2.000 [ 0.003 : 3.000] Elapsed count f( 65,536): 131,071: 2.000 [ 0.007 : 2.333] Elapsed count f( 131,072): 262,143: 2.000 [ 0.002 : 0.286] Elapsed count f( 262,144): 524,287: 2.000 [ 0.003 : 1.500] Elapsed count f( 524,288): 1,048,575: 2.000 [ 0.007 : 2.333] Elapsed count f( 1,048,576): 2,097,151: 2.000 [ 0.015 : 2.143] Elapsed count f( 2,097,152): 4,194,303: 2.000 [ 0.028 : 1.867] Elapsed count f( 4,194,304): 8,388,607: 2.000 [ 0.043 : 1.536] Elapsed count f( 8,388,608): 16,777,215: 2.000 [ 0.055 : 1.279] Elapsed count f( 16,777,216): 33,554,431: 2.000 [ 0.147 : 2.673] Elapsed count f( 33,554,432): 67,108,863: 2.000 [ 0.360 : 2.449] Elapsed count f( 67,108,864): 134,217,727: 2.000 [ 0.597 : 1.658] Average delta: 2.000
N pushes in linear time
Each time we resize: constant pushes double
Each push is amortized constant time