[알고리즘] 배열로 구현하는 스택(stack)
// 배열로 구현하는 스택
3
2
1
Pop 3
Stack contents : Top ----> Bottom
2
1
Push 4, 5, 6
Stack contents : Top ----> Bottom
6
5
4
2
1
Now stack is full, push 7
Stack overflow.
Stack contents : Top ----> Bottom
6
5
4
2
1
Initialize stack
Stack contents : Top ----> Bottom
Now stack is empty
Pop
Stack underflow.
Push 7, 8
Stack contents : Top ----> Bottom
8
7
// 스택 최대크기 5
define('MAX', 5);
$top = 0;
$stack = array();
function init_stack() {
Global $top;
$top = -1;
}
function push($t) {
Global $top, $stack;
if ($top >= MAX - 1) {
println('Stack overflow.');
return -1;
}
$stack[++$top] = $t;
}
function pop() {
Global $top, $stack;
if ($top < 0) {
println('Stack underflow.');
return -1;
}
return $stack[$top--];
}
function print_stack() {
Global $top, $stack;
println('Stack contents : Top ----> Bottom');
for ($i = $top; $i >= 0; $i--)
println($stack[$i]);
}
init_stack();
println('Push 1, 2, 3');
push(1);
push(2);
push(3);
print_stack();
println();
$i = pop();
println("Pop ". $i);
print_stack();
println();
println('Push 4, 5, 6');
push(4);
push(5);
push(6);
print_stack();
println();
println('Now stack is full, push 7');
push(7);
print_stack();
println();
println('Initialize stack');
init_stack();
print_stack();
println();
println('Now stack is empty');
println('Pop');
pop();
println('Push 7, 8');
push(7);
push(8);
print_stack();
println();
function println($val='') {
echo $val.'<br />';
}
/* output
Push 1, 2, 3
Stack contents : Top ----> Bottom3
2
1
Pop 3
Stack contents : Top ----> Bottom
2
1
Push 4, 5, 6
Stack contents : Top ----> Bottom
6
5
4
2
1
Now stack is full, push 7
Stack overflow.
Stack contents : Top ----> Bottom
6
5
4
2
1
Initialize stack
Stack contents : Top ----> Bottom
Now stack is empty
Pop
Stack underflow.
Push 7, 8
Stack contents : Top ----> Bottom
8
7
*/
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function println($val='') {
echo $val.'<br />';
}
function 보지 못했습니다.^^
나는 또 println 함수가 php 에서 내장함수 추가했는줄 알았습니다.^^