24点|穷举法【待续】

<?php/* * 1.位置固定 * 2.没有去重 */calculate24(8,3,8,3);function calculate24($a,$b,$c,$d){define("DELTA", 0.00000001);print_formula1($a, $b, $c, $d);print_formula2($a, $b, $c, $d);print_formula3($a, $b, $c, $d);print_formula4($a, $b, $c, $d);print_formula5($a, $b, $c, $d);}// formula1: (a op b) op c) op d function print_formula1($a,$b,$c,$d) {//echo DELTA;exit;for($opt1 = 1; $opt1 <= 4; $opt1++) {$result_ab = 0;$result_ab = operate($a, $b, $opt1);for($opt2 = 1; $opt2 <= 4; $opt2++) {$result_abc = 0;$result_abc = operate($result_ab,$c,$opt2);for($opt3 = 1; $opt3 <= 4; $opt3++){$result_abcd = 0;$result_abcd = operate($result_abc, $d, $opt3);if( abs($result_abcd - 24) < DELTA) {printf("((%d %s %d) %s %d) %s %d = 24\n",$a,symbolize($opt1),$b,symbolize($opt2),$c,symbolize($opt3),$d);echo "<br />";}}}}}// formula2: (a op b) op (c op d)function print_formula2($a,$b,$c,$d) {for($opt1 = 1; $opt1 <= 4; $opt1++) {$result_ab = 0;$result_ab = operate($a, $b, $opt1);for($opt3 = 1; $opt3 <= 4; $opt3++) {$result_cd = 0;$result_cd = operate($c,$d,$opt3);for($opt2 = 1; $opt2 <= 4; $opt2++){$result_abcd = 0;$result_abcd = operate($result_ab, $result_cd, $opt2);if( abs($result_abcd - 24) < DELTA) {printf("(%d %s %d) %s (%d %s %d) = 24\n",$a,symbolize($opt1),$b,symbolize($opt2),$c,symbolize($opt3),$d);echo "<br />";}}}}}// formula3: (a op (b op c)) op d  function print_formula3($a,$b,$c,$d) {for($opt2 = 1; $opt2 <= 4; $opt2++) {$result_bc = 0;$result_bc = operate($b, $c, $opt2);for($opt1 = 1; $opt1 <= 4; $opt1++) {$result_abc = 0;$result_abc = operate($a,$result_bc,$opt1);for($opt3 = 1; $opt3 <= 4; $opt3++){$result_abcd = 0;$result_abcd = operate($result_abc, $d, $opt3);if( abs($result_abcd - 24) < DELTA) {printf("(%d %s (%d %s %d)) %s %d = 24\n",$a,symbolize($opt1),$b,symbolize($opt2),$c,symbolize($opt3),$d);echo "<br />";}}}}}// formula4: a op ((b op c) op d) function print_formula4($a,$b,$c,$d) {for($opt2 = 1; $opt2 <= 4; $opt2++) {$result_bc = 0;$result_bc = operate($b, $c, $opt2);for($opt3 = 1; $opt3 <= 4; $opt3++) {$result_bcd= 0;$result_bcd = operate($result_bc,$d,$opt3);for($opt1 = 1; $opt1 <= 4; $opt1++){$result_abcd = 0;$result_abcd = operate($a, $result_bcd, $opt1);if( abs($result_abcd - 24) < DELTA) {printf("%d %s ((%d %s %d) %s %d) = 24\n",$a,symbolize($opt1),$b,symbolize($opt2),$c,symbolize($opt3),$d);echo "<br />";}}}}}// formula5: a op (b op (c op d)) function print_formula5($a,$b,$c,$d) {for($opt3 = 1; $opt3 <= 4; $opt3++) {$result_cd = 0;$result_cd = operate($c, $d, $opt3);for($opt2 = 1; $opt2 <= 4; $opt2++) {$result_bcd = 0;$result_bcd = operate($b,$result_cd,$opt2);for($opt1 = 1; $opt1 <= 4; $opt1++){$result_abcd = 0;$result_abcd = operate($a, $result_bcd, $opt1);if( abs($result_abcd - 24) < DELTA) {printf("%d %s (%d %s (%d %s %d)) = 24\n",$a,symbolize($opt1),$b,symbolize($opt2),$c,symbolize($opt3),$d);echo "<br />";}}}}}function operate($a,$b,$opt) {switch($opt) {case 1:return $a + $b;case 2:return $a - $b;case 3:return $a * $b;case 4:if(0 == $b){break;}return $a / $b;}}function symbolize($opt) {switch($opt) {case 1 :return "+";case 2 :return "-";case 3 :return "*";case 4 :return "/";}}

更好的办法【待续】：http://maider.blog.sohu.com/210577392.html

http://blog.csdn.net/sunnianzhong/article/details/8739042