Find Cube Pairs | Set 2 ( A n ^ ( 1 / 3 ) Solution ) | Function to find pairs that can represent the given number as sum of two cubes ; find cube root of n ; create a array of size of size ' cubeRoot ' ; for index i , cube [ i ] will contain i ^ 3 ; Find all pairs in above sorted array cube [ ] whose sum is equal to n ; Driver code
< ? php function findPairs ( $ n ) { $ cubeRoot = pow ( $ n , 1.0 / 3.0 ) ; $ cube = array ( ) ; for ( $ i = 1 ; $ i <= $ cubeRoot ; $ i ++ ) $ cube [ $ i ] = $ i * $ i * $ i ; $ l = 1 ; $ r = $ cubeRoot ; while ( $ l < $ r ) { if ( $ cube [ $ l ] + $ cube [ $ r ] < $ n ) $ l ++ ; else if ( $ cube [ $ l ] + $ cube [ $ r ] > $ n ) $ r -- ; else { echo " ( " , $ l , " , ▁ " , floor ( $ r ) , " ) " ; echo " STRNEWLINE " ; $ l ++ ; $ r -- ; } } } $ n = 20683 ; findPairs ( $ n ) ; ? >