Codeforces 461C Appleman and a Sheet of Paper(模拟)

#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;
const int maxn = 1e6+5;

int N, Q, W[maxn];

int main () {
scanf("%d%d", &N, &Q);
for (int i = 1; i <= N; i++)
W[i] = i;

bool flag = false;
int k, l, r;
int n = N, bw = 0;

while (Q--) {
scanf("%d%d", &k, &l);

if (k == 1) {
if (l > n - l) {
flag = !flag;
l = n - l;
}

if (flag) {

for (int i = 0; i < l; i++)
W[bw + n - l - i] += N - W[bw + n - l + i];

} else {
bw += l;
for (int i = 0; i < l; i++)
W[bw + i] -= W[bw - i];
}
n -= l;

} else {
scanf("%d", &r);
if (flag) {
int tmp = n - r;
r = n - l;
l = tmp;
}
printf("%d\n", W[bw + r] - W[bw + l]);
}
}
return 0;
}