Color Sequence

 

状态压缩，比较相同状态取数

https://ac.nowcoder.com/acm/contest/13175/E

#include<bits/stdc++.h>
#define inf 1e18
#define ll long long
#define MAX 1000001
const ll N = 1e6+7;
const ll M = 3e6+7;
const ll mod = 1e9+7;
using namespace std;
int n,a[N];
int point[N];
int mp[M];
int main(){
    scanf("%d",&n);
    for(int i=1;i<=n;++i)    scanf("%d",&a[i]);
    for(int i=1;i<=n;++i){
        point[i]=point[i-1];
        
        if((point[i]>>a[i])&1)    point[i]-=(1ll<<a[i]);
        else                    point[i]+=(1ll<<a[i]);
    }
    for(int i=0;i<=n;++i){
        mp[point[i]]++;
    }
    ll ans=0; 
    for(int i=0;i<=n;++i){
        mp[point[i]]--;
        ans+=mp[point[i]];
    }
    printf("%lld\n",ans);
    return 0; 
}