question: public static void fillFourthQuadrantWithSectorPoints ( int radius , Map < String , Point > sector , List < String > indexesKeys , Map < String , Integer > keysIndexes ) { if ( SHOW_LOGS ) Log . v ( TAG , ">> fillFourthQuadrantWithSectorPoints, size " + sector . size ( ) ) ; for ( int y = 1 ; y <= radius ; y ++ ) { int x = ( int ) Math . sqrt ( Math . pow ( radius , 2 ) - Math . pow ( y , 2 ) ) ; String key = getSectorKey ( x , y ) ; if ( SHOW_LOGS ) Log . v ( TAG , "fillFourthQuadrantWithSectorPoints, key[" + key + "]" ) ; indexesKeys . add ( key ) ; keysIndexes . put ( key , indexesKeys . size ( ) - 1 ) ; sector . put ( key , new Point ( x , y ) ) ; } if ( SHOW_LOGS ) Log . v ( TAG , "<< fillFourthQuadrantWithSectorPoints" ) ; }
target:  | |         x ------|----------> |           The formula is R^2 = x^2 + y^2 |           We are calculating a circle points. |           Start and y=1 and increment y up to "radius" y V