[CSP-S 2019]括号树

[CSP-S 2019]括号树

源代码：

#include<cstdio>
#include<cctype>
#include<vector>
inline int getint() {
	register char ch;
	while(!isdigit(ch=getchar()));
	register int x=ch^'0';
	while(isdigit(ch=getchar())) x=(((x<<2)+x)<<1)+(ch^'0');
	return x;
}
inline bool isbracket(const char &ch) {
	return ch=='('||ch==')';
}
inline bool getbracket() {
	register char ch;
	while(!isbracket(ch=getchar()));
	return ch==')';
}
typedef long long int64;
const int N=5e5+1;
std::vector<int> e[N];
inline void add_edge(const int &u,const int &v) {
	e[u].push_back(v);
}
bool c[N];
int stk[N],par[N],dep[N],top[N];
int64 f[N];
void dfs(const int &x) {
	dep[x]=dep[par[x]]+1;
	stk[dep[x]]=x;
	//f[x]: end with current char
	if(x!=1&&c[x]&&!c[par[x]]) {//"..." + "()"
		f[x]=1+f[par[par[x]]];
		top[x]=top[par[par[x]]]?:par[x];
	}
	if(x!=1&&c[x]&&c[par[x]]) {//"(" + "(...)" + ")"
		if(top[par[x]]>1&&!c[par[top[par[x]]]]) {
			f[x]=1+f[par[par[top[par[x]]]]];
			top[x]=top[par[par[top[par[x]]]]]?:par[top[par[x]]];
		}
	}
	for(unsigned i=0;i<e[x].size();i++) {
		dfs(e[x][i]);
	}
}
int main() {
	freopen("brackets.in","r",stdin);
	freopen("brackets.out","w",stdout);
	const int n=getint();
	for(register int i=1;i<=n;i++) {
		c[i]=getbracket();
	}
	for(register int i=2;i<=n;i++) {
		par[i]=getint();
		add_edge(par[i],i);
	}
	dfs(1);
	for(register int i=2;i<=n;i++) {
		f[i]+=f[par[i]];
	}
	int64 ans=0;
	for(register int i=1;i<=n;i++) {
		ans^=f[i]*i;
	}
	printf("%lld
",ans);
	return 0;
}