A 思维
代码语言：javascript复制#pragma GCC target("avx,sse2,sse3,sse4,popcnt")
#pragma GCC optimize("O2,O3,Ofast,inline,unroll-all-loops,-ffast-math")
#include <bits/stdc .h>
using namespace std;
#define js ios::sync_with_stdio(false);cin.tie(0); cout.tie(0)
typedef long long ll; typedef unsigned long long ull; typedef long double ld;
const ll MOD = 1e9 7;
inline ll read() { ll s = 0, w = 1; char ch = getchar(); while (ch < 48 || ch > 57) { if (ch == '-') w = -1; ch = getchar(); } while (ch >= 48 && ch <= 57) s = (s << 1) (s << 3) (ch ^ 48), ch = getchar(); return s * w; }
inline void write(ll x) { if (!x) { putchar('0'); return; } char F[40]; ll tmp = x > 0 ? x : -x; if (x < 0)putchar('-'); int cnt = 0; while (tmp > 0) { F[cnt ] = tmp % 10 '0'; tmp /= 10; } while (cnt > 0)putchar(F[--cnt]); }
inline ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll qpow(ll a, ll b) { ll ans = 1; while (b) { if (b & 1) ans *= a; b >>= 1; a *= a; } return ans; } ll qpow(ll a, ll b, ll mod) { ll ans = 1; while (b) { if (b & 1)(ans *= a) %= mod; b >>= 1; (a *= a) %= mod; }return ans % mod; }
inline int lowbit(int x) { return x & (-x); }
int main(){
int t;
cin>>t;
while(t--){
int n;
cin>>n;
if(n<=30) cout<<"NO"<<endl;
else if(n==36) cout<<"YESn"<<"5 6 10 15"<<endl;
else if (n==40) cout<<"YESn"<<"2 6 10 22"<<endl;
else if (n==44) cout<<"YESn"<<"2 6 10 26"<<endl;
else cout<<"YESn"<<"6 10 14 "<<n-30<<endl;
}
} B 观察
代码语言：javascript复制#pragma GCC target("avx,sse2,sse3,sse4,popcnt")
#pragma GCC optimize("O2,O3,Ofast,inline,unroll-all-loops,-ffast-math")
#include <bits/stdc .h>
using namespace std;
#define js ios::sync_with_stdio(false);cin.tie(0); cout.tie(0)
typedef long long ll; typedef unsigned long long ull; typedef long double ld;
const ll MOD = 1e9 7;
inline ll read() { ll s = 0, w = 1; char ch = getchar(); while (ch < 48 || ch > 57) { if (ch == '-') w = -1; ch = getchar(); } while (ch >= 48 && ch <= 57) s = (s << 1) (s << 3) (ch ^ 48), ch = getchar(); return s * w; }
inline void write(ll x) { if (!x) { putchar('0'); return; } char F[40]; ll tmp = x > 0 ? x : -x; if (x < 0)putchar('-'); int cnt = 0; while (tmp > 0) { F[cnt ] = tmp % 10 '0'; tmp /= 10; } while (cnt > 0)putchar(F[--cnt]); }
inline ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll qpow(ll a, ll b) { ll ans = 1; while (b) { if (b & 1) ans *= a; b >>= 1; a *= a; } return ans; } ll qpow(ll a, ll b, ll mod) { ll ans = 1; while (b) { if (b & 1)(ans *= a) %= mod; b >>= 1; (a *= a) %= mod; }return ans % mod; }
inline int lowbit(int x) { return x & (-x); }
int main(){
int t;
cin>>t;
int n;
while(t--){
cin>>n;
int len=4*n-n;
for (int i=0;i<(len/4);i ) cout<<9;
for (int i=(len/4);i<n;i ) cout<<8;
cout<<endl;
}
return 0;
}C dfs 这题卡时间较长
代码语言：javascript复制#include<bits/stdc .h>
#define maxn 100100
using namespace std;
vector<int> g[maxn];
int happy[maxn];
int all[maxn];
int diff[maxn];
int flag;
int f;
void dfs(int v, int p) {
int h = 0,k = 0;
for (auto u : g[v]){
k = 1;
if (u == p) {
continue;
}
dfs(u, v);
all[v] = all[u];
h = happy[u];
}
happy[v] = all[v] - (all[v] - diff[v]) / 2;
if (happy[v] < h || happy[v]<0||happy[v]>all[v] || all[v]%2!=(diff[v]%2 2)%2) {
f = 0;
}
}
int main(){
int t;
cin>>t;
while(t--){
f = 1;
int n,m;
cin>>n>>m;
for (int i = 0; i < n; i ) {
cin >> all[i];//每个人住在哪
g[i].clear();
}
for (int i = 0; i < n; i ) {
cin >> diff[i];//给定的对照值
}
for (int i=0;i<n-1;i ){//建图
int a, b;
cin>>a>>b;
a--;
b--;
g[a].push_back(b);
g[b].push_back(a);
}
dfs(0, -1);
if(f) cout << "YES"<<endl;
else cout << "NO" <<endl;
}
return 0;
}D 不太理解，队友做了
