自闭教室

这一场非常奇怪。

A.

#include <stdio.h>
inline int F() { register int aa , bb , ch;
	while(ch = getchar() , (ch<'0'||ch>'9') && ch != '-'); ch == '-' ? aa=bb=0 : (aa=ch-'0',bb=1);
	while(ch = getchar() , ch>='0'&&ch<='9') aa = aa*10 + ch-'0'; return bb ? aa : -aa;
}
int n , a[100010];
int main() {
	n = F();
	if(n == 1) {
		int qwq = F();
		if(qwq == 15) puts("DOWN");
		else if(qwq == 0) puts("UP");
		else puts("-1");
		return 0;
	}
	for(int i=1; i<=n; ++i) {
		a[i] = F();
	}
	if(a[n] < a[n-1]) {
		if(a[n] == 0) puts("UP");
		else puts("DOWN");
	}
	else {
		if(a[n] == 15) puts("DOWN");
		else puts("UP");
	}
}

B.

#include <stdio.h>
#include <iostream>
using std::max; using std::min;
inline int F() { register int aa , bb , ch;
	while(ch = getchar() , (ch<'0'||ch>'9') && ch != '-'); ch == '-' ? aa=bb=0 : (aa=ch-'0',bb=1);
	while(ch = getchar() , ch>='0'&&ch<='9') aa = aa*10 + ch-'0'; return bb ? aa : -aa;
}
const int Maxn = 100010;
int n , a[Maxn] , ans1 , ans2 , ans; char s[Maxn];
int main() {
	n = F();
	scanf("%s",s+1);
	for(int i=1; i<=n; ++i) {
		if(s[i] == 'b') a[i] = 1;
		else a[i] = 0;
	}
	for(int i=1 , p = 0; i<=n; ++i , p ^= 1) {
		if(a[i] != p) {
			if(p) ++ans1;
			else ++ans2;
		}
	}
	ans = max(ans1,ans2);
	ans1 = ans2 = 0;
	for(int i=1; i<=n; ++i) {
		if(s[i] == 'b') a[i] = 1;
		else a[i] = 0;
	}
	for(int i=1 , p = 1; i<=n; ++i , p ^= 1) {
		if(a[i] != p) {
			if(p) ++ans1;
			else ++ans2;
		}
	}
	ans = min(ans , max(ans1,ans2));
	printf("%d\n",ans);
}

C.

#include <stdio.h>
#include <iostream>
using std::min; using std::max;
const int mod = 1000000007;
inline int F() { register int aa , bb , ch;
	while(ch = getchar() , (ch<'0'||ch>'9') && ch != '-'); ch == '-' ? aa=bb=0 : (aa=ch-'0',bb=1);
	while(ch = getchar() , ch>='0'&&ch<='9') aa = aa*10 + ch-'0'; return bb ? aa : -aa;
}
const int Maxt = 819210;
struct node { int a[2][2]; } lzy , lazy[Maxt] , tree[Maxt] , Std , f1 , Nul;
node operator + (node a , node b) {
	a.a[0][0] = (a.a[0][0] + b.a[0][0]) % mod;
	a.a[1][0] = (a.a[1][0] + b.a[1][0]) % mod;
	a.a[0][1] = (a.a[0][1] + b.a[0][1]) % mod;
	a.a[1][1] = (a.a[1][1] + b.a[1][1]) % mod;
	return a;
}
node operator * (node a , node b) {
	node c;
	for(int i=0; i<2; ++i)
		for(int j=0; j<2; ++j) {
			c.a[i][j] = 0;
			for(int k=0; k<2; ++k)
				c.a[i][j] = (c.a[i][j] + (long long)a.a[i][k]*b.a[k][j]) % mod;
		}return c;
}
node pow(node tmp , int i) {
	node ans = Std;
	for(; i; i>>=1 , tmp = tmp*tmp) if(i&1) ans = ans*tmp;
	return ans;
}
const int Maxn = 100010;
int n , m , ll[Maxt] , rr[Maxt] , a[Maxn];

void update(int x) {
	if(ll[x] == rr[x]) tree[x] = lazy[x];
	else tree[x] = (tree[x<<1] + tree[x<<1|1]) * lazy[x];
}
void Build(int x , int l  , int r) {
	ll[x] = l; rr[x] = r; lazy[x] = Std;
	if(l == r) {
		lazy[x] = pow(f1,a[l]);
	}
	else {
		int mid = (l + r) >> 1;
		Build(x<<1 , l , mid);
		Build(x<<1|1 , mid+1 , r);
	}
	update(x);
}

void modify(int x , int l , int r) {
	l = max(ll[x] , l); r = min(rr[x] , r);
	if(l > r) return;
	if(ll[x] == l && rr[x] == r) lazy[x] = lazy[x] * lzy;
	else {
		modify(x<<1 , l , r);
		modify(x<<1|1 , l , r);
	}
	update(x);
}

node query(int x , int l , int r) {
	l = max(ll[x] , l); r = min(rr[x] , r);
	if(l > r) return Nul;
	if(l == ll[x] && r == rr[x]) return tree[x];
	return (query(x<<1 , l , r) + query(x<<1|1 , l , r)) * lazy[x];
}

int main() {
	f1.a[0][0] = f1.a[1][0] = f1.a[0][1] = 1; f1.a[1][1] = 0;
	Std.a[0][0] = Std.a[1][1] = 1; Std.a[0][1] = Std.a[1][0] = 0;
	Nul.a[0][0] = Nul.a[0][1] = Nul.a[1][0] = Nul.a[1][1] = 0;
	n = F() , m = F();
	for(int i=1; i<=n; ++i)
		a[i] = F();
	Build(1,1,n);
	while(m--) {
		int flag = F() , l = F() , r = F();
		if(flag == 1) {
			int v = F();
			lzy = pow(f1,v);
			modify(1,l,r);
		}
		else printf("%d\n",query(1,l,r).a[0][1]);
	}
}