Wannafly挑战赛1AdfsB思维,枚举

#include
using namespace std;
#pragma comment(linker, "/STACK:102400000,102400000")
#define rep(i,a,b) for (int i&＃61;a; i<&＃61;b; &＃43;&＃43;i)
#define per(i,b,a) for (int i&＃61;b; i>&＃61;a; --i)
#define mes(a,b) memset(a,b,sizeof(a))
#define INF 0x3f3f3f3f
#define MP make_pair
#define PB push_back
#define fi first
#define se second
#define PII pair
typedef long long ll;
const int N &＃61; 100005;int n, x, y;
vector<int > G[N];
PII dfs(int u, int fa)
{if(G[u].size()&＃61;&＃61;1) return MP(0,0);PII ans&＃61;MP(0,0), tmp;for(int i&＃61;0, to; to&＃61;G[u][i], ii)if(to!&＃61;fa){tmp &＃61; dfs(to, u);ans.fi &＃43;&＃61; tmp.se&＃43;1;ans.se &＃43;&＃61; tmp.fi;}return ans;
}
int main()
{scanf("%d", &n);rep(i,1,n-1){scanf("%d%d", &x, &y);G[x].PB(y); G[y].PB(x);}PII ans &＃61; dfs(1, 0);&＃43;&＃43;ans.se;printf("%lld\n", ans.fi*(ans.fi-1)/2 &＃43; ans.se*(ans.se-1)/2 );return 0;
}

#include
using namespace std;
#pragma comment(linker, "/STACK:102400000,102400000")
#define rep(i,a,b) for (int i&＃61;a; i<&＃61;b; &＃43;&＃43;i)
#define per(i,b,a) for (int i&＃61;b; i>&＃61;a; --i)
#define mes(a,b) memset(a,b,sizeof(a))
#define INF 0x3f3f3f3f
#define MP make_pair
#define PB push_back
#define fi first
#define se second
typedef long long ll;
const int N &＃61; 100005, M &＃61; 2000005;int n, s[N];
ll ans, cnt[M];
int main()
{scanf("%d", &n);int ai;rep(i,1,n){scanf("%d", &ai);s[i] &＃61; s[i-1]^ai;}rep(i,1,n)rep(j,i,n)&＃43;&＃43;cnt[s[j]^s[i-1]];rep(i,1,n){rep(j,i,n)--cnt[s[j]^s[i-1]];rep(j,1,i)ans &＃43;&＃61; cnt[s[i]^s[j-1]];}printf("%lld\n", ans);return 0;
}