stack的应用
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#include<iostream>#include<stack>#include<stdio.h>#include<stdlib.h>#include<string.h>#define MAX 128using
namespace
std;
stack<char
*> back_stack;
stack<char
*> forward_stack;
int
main() {
char
raw[MAX];
char
* now;
char
* s;
now = (char
*)malloc(sizeof(char) * 128);
while(1) {
cin >> raw;
if(raw[0] == ‘Q‘) {
break;
}
if(raw[0] == ‘V‘) {
cin >> raw;
back_stack.push(now);
s = (char
*)malloc(sizeof(char) * MAX);
strcpy(s, raw);
now = s;
printf("%s\n", s);
while(!forward_stack.empty()) {
forward_stack.pop();
}
}
else
if(raw[0] == ‘B‘) {
if(back_stack.size() == 0) {
printf("Ignored\n");
}
else
{
s = back_stack.top();
back_stack.pop();
printf("%s\n", s);
forward_stack.push(now);
now = s;
}
}
else
if(raw[0] == ‘F‘) {
if(forward_stack.size() == 0) {
printf("Ignored\n");
}
else
{
s = forward_stack.top();
forward_stack.pop();
printf("%s\n", s);
back_stack.push(now);
now = s;
}
}
else
{
;
}
}
while(back_stack.size() != 0) {
s = back_stack.top();
free(s);
back_stack.pop();
}
while(forward_stack.size() != 0) {
s = forward_stack.top();
free(s);
forward_stack.pop();
}
return
0;
} |