Question

I Have 3 Arrays

Array 1 :

 Array ( [0] => 0 [1] => 256 [2] => 512 [3] => 768 [4] => 1024 [5] => 1280 [6] => 1536 [7] => 1792 [8] => 2048 [9] => 2304 [10] => 2560 [11] => 2816 [12] => 3072 [13] => 3328 [14] => 3584 [15] => 3840 [16] => 4096 [17] => 4352 [18] => 4608 [19] => 4864 [20] => 5120 [21] => 5376 [22] => 5632 [23] => 5888 )

Array 2 :

Array ( [0] => 0 [1] => 65536 [2] => 131072 [3] => 196608 [4] => 262144 [5] => 327680 [6] => 393216 [7] => 458752 [8] => 524288 [9] => 589824 [10] => 655360 [11] => 720896 [12] => 786432 [13] => 851968 [14] => 917504 [15] => 983040 [16] => 1048576 [17] => 1114112 [18] => 1179648 [19] => 1245184 [20] => 1310720 [21] => 1376256 [22] => 1441792 [23] => 1507328 [24] => 1572864 [25] => 1638400 [26] => 1703936 [27] => 1769472 [28] => 1835008 [29] => 1900544 [30] => 1966080 [31] => 2031616 )

Array 3 :

Array ( [0] => 0 [1] => 1 [2] => 2 [3] => 3 [4] => 4 [5] => 5 [6] => 6 [7] => 7 [8] => 8 [9] => 9 [10] => 10 [11] => 11 [12] => 12 [13] => 13 [14] => 14 [15] => 15 [16] => 16 [17] => 17 [18] => 18 [19] => 19 [20] => 20 [21] => 21 [22] => 22 [23] => 23 [24] => 24 [25] => 25 [26] => 26 [27] => 27 [28] => 28 [29] => 29 [30] => 30 [31] => 31 )

Given a number X which I know was calculated as a1[i] + a2[j] + a3[k] how can I calculate i, j and k?

Examples:

1. X = 458752 => i=0, j=7, k=0 which is 458752 = 0 + 458752 + 0
2. X = 131586 => i=2, j=2, k=2 which is 131586 = 256 + 131072 + 2
3. X = 65793 => i=1, j=1, k=1 which is 65793 = 256 + 65536 + 1

Answer 1

How about:

foreach(array(458752, 131586, 65793) as $x) {
    $j = intval($x / 65536);
    $x = $x % 65536;
    $i = intval($x / 256);
    $k = $x % 256;
    echo "x=$x, i=$i, j=$j, k=$k\n";
}

output:

x=0, i=0, j=7, k=0
x=514, i=2, j=2, k=2
x=257, i=1, j=1, k=1