2018頭條春招筆試題解
阿新 • • 發佈：2019-02-12
頭條測試: https://blog.csdn.net/flushhip/article/details/79562199
第一題： 雙指標：
#include <bits/stdc++.h>using namespace std;typedef long long ll;const int N = 1e6+7;int a[N];int main(){int n,k;scanf("%d%d",&n,&k);for(int i=0;i<n;++i) scanf("%d",&a[i]);sort(a, a+n);n = unique(a, a+n) -a;int r = 0, ans=0;for(int l=0; l<n;++l){while(r<n&&a[r]-a[l]<k) ++r;if(r==n) break;if(a[r]-a[l] == k) ++ans;}printf("%d\n", ans);return 0;} |
#include <bits/stdc++.h>using namespace std;typedef pair<int,int> pii;map<pair<int,int> , int > mp;int main(){int n;scanf("%d",&n);queue<pii> q;q.push(make_pair(1, 1));mp[make_pair(1,1)]=0;while(!q.empty()){pii pr = q.front();q.pop();// printf("%d %d\n",pr.first, pr.second);if(pr.first == n){printf("%d\n", mp[pr]);exit(0);}pii t=pr;t.second = t.first; t.first*=2;if(!mp.count(t)){q.push(t);mp[t] = mp[pr]+1;}t=pr;t.first=t.first+t.second;if(!mp.count(t)){q.push(t);mp[t] = mp[pr]+1;}}return 0;} |
#include <bits/stdc++.h>using namespace std;typedef long long ll;char s[107];char G[5][10][8] = {{"66666", "....6", "66666", "66666", "6...6", "66666", "66666", "66666", "66666", "66666"},{"6...6", "....6", "....6", "....6", "6...6", "6....", "6....", "....6", "6...6", "6...6"},{"6...6", "....6", "66666", "66666", "66666", "66666", "66666", "....6", "66666", "66666"},{"6...6", "....6", "6....", "....6", "....6", "....6", "6...6", "....6", "6...6", "....6"},{"66666", "....6", "66666", "66666", "....6", "66666", "66666", "....6", "66666", "66666"}};ll cal(){int n = strlen(s);ll sum=0, cur=0, prd=1;for(int i=0; i<n; ++i){if(isdigit(s[i])) cur=cur*10+s[i]-'0';else if(s[i] == '-'){sum+=prd*cur;cur=0;prd=-1;}else if(s[i] == '+'){sum+=prd*cur;cur=0;prd=1;}else{prd*=cur;cur=0;}}return sum+prd*cur;}int main(){int T;scanf("%d",&T);while(T--){scanf("%s", s);ll ans = cal();for(int i=0; i<5; ++i){vector<int> v;ll tmp = ans;while(tmp) v.push_back(tmp%10),tmp/=10;reverse(v.begin(), v.end());if(v.empty()) v.push_back(0);for(int j=0; j<v.size(); ++j){printf("%s%s",G[i][v[j]], j+1==v.size()?"\n":"..");}}}return 0;} |
| 1 |
放數只能放沒出現過的數
從小的數開始放可以使均值小的集合均值上升慢，均值大的集合均值上升快，這樣最優。
#include <bits/stdc++.h>using namespace std;typedef long long ll;set<int> sa,sb;ll suma, sumb;const long double eps = 1e-14;inline int cmp(long double a, long double b){if(fabs(a-b) <= eps) return 0;return a>b?1:-1;}inline long double jz(ll k, int m){return (long double)k/m;}int main(){int n,m;scanf("%d%d",&n,&m);for(int i=0; i<n;++i){int t;scanf("%d",&t);sa.insert(t);suma+=t;}for(int i=0;i<m;++i){int t;scanf("%d",&t);sb.insert(t);sumb+=t;}if(cmp(jz(suma, n), jz(sumb, m))==-1){swap(suma, sumb);swap(n, m);sa.swap(sb);}int mx =n;int ans = 0;for(auto k : sa){if(cmp(k, jz(suma, n)) >= 0) break;// printf("%d %d\n",n, k);if(!sb.count(k)&&cmp(k, jz(sumb, m))>0){++ans;sumb+=k;suma-=k;sb.insert(k);--n;++m;}}printf("%d\n", ans); |
第五題：BFS
#include <bits/stdc++.h>using namespace std;const int N = 1e5+1000;typedef pair<int, int> pii;bool vis[N];int a[N];int main(){int n,k,h;scanf("%d%d%d",&n,&k,&h);for(int i=0;i<n;++i){int t;scanf("%d",&t);a[t]=1;}queue<pii> q;q.push({0,0});int ans = 0;while(!q.empty()){pii p = q.front(); q.pop();if(p.second>k) break;ans = max(ans, p.first);for(int i=1; i<=h; ++i){if(a[p.first + i]&&!vis[p.first+2*i]){vis[p.first+2*i]=true;q.push(make_pair(p.first+2*i, p.second+1));}if(p.first-2*i>0&&a[p.first-i]&&!vis[p.first-2*i]){vis[p.first-2*i]=true;q.push(make_pair(p.first-2*i, p.second+1));}}}printf("%d\n", ans);return 0;} |