AtCoder Regular Contest 075 D Widespread
这道题其实二分一下答案就okay了的 不过LL什么的有时候忘了加 被卡了下
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#include<cstdio> #include<cstring> #include<algorithm> #define LL long long using namespace std; const int M=100007; int read(){ int ans=0,f=1,c=getchar(); while(c<'0'||c>'9'){if(c=='-') f=-1; c=getchar();} while(c>='0'&&c<='9'){ans=ans*10+(c-'0'); c=getchar();} return ans*f; } int n,p,q,w; int s[M]; LL ans; bool check(LL x){ LL now=x*q,tot=0; int top=n,v; while(top){ if(s[top]<=now) break; if((s[top]-now)%w) v=(s[top]-now)/w+1; else v=(s[top]-now)/w; tot+=v; top--; } return tot<=x; } int main() { n=read(); p=read(); q=read(); w=p-q; for(int i=1;i<=n;i++) s[i]=read(); sort(s+1,s+1+n); LL l=0,r=1e9; while(l<=r){ LL mid=(l+r)>>1; if(check(mid)) ans=mid,r=mid-1; else l=mid+1; } printf("%lld\n",ans); return 0; }