bzoj2460: [BeiJing2011]元素

题目链接

bzoj2460: [BeiJing2011]元素

题解

贪心维护线性基..
直接(1 << x)会爆int，很惨

代码

#include<cstdio>
#include<iostream> 
#include<algorithm> 
#define LL long long 
LL read() {
	LL x = 0,f = 1;
	char c = getchar(); 
	while(c < '0' || c >'9')c = getchar(); 
	while(c <= '9' && c >= '0')x = x * 10 + c - '0',c = getchar(); 
	return x; 
} 
struct node {
	LL a;int b; 
	bool operator < (const node &x)const { 
		return b > x.b; 
	} 	
} a[1007]; 
int b[67]; 
LL bin[67]; 
int main() { 
	bin[0] = 1;for(int i = 1;i <= 63;++ i) bin[i] = bin[i - 1] << 1; 
	int n = read(); 
	int ans = 0; 	
	for(int i = 1;i <= n;++ i) a[i].a = read(),a[i].b = read(); 
	std::sort(a + 1,a + n +1); 
	for(int i = 1;i <= n;++ i) { 
		for(LL j = 63;j >= 0;-- j) {
			if(a[i].a & bin[j]) { 
				if(!b[j]) { b[j] = i;break;} 
				else a[i].a ^= a[b[j]].a; 
			} 
		} 
		if(a[i].a) ans += a[i].b; 
	} 
	printf("%d
",ans); 
	return 0;
}