contest 1.21

A.Exchange

模拟

#include <iostream>
#include<cstdio>
typedef long long ll;
using namespace std;

int main()
{
    ll a,b,k;scanf("%lld%lld%lld",&a,&b,&k);
    ll cnt=0;
    while(k--){
        cnt++;
        if(cnt%2){
          if(a%2) a--;
          b+=a/2;
          a=a/2;
        }
        else{
          if(b%2) b--;
          a+=b/2;
          b=b/2;
        }
    }
    printf("%lld %lld
",a,b);
    return 0;
}

B.Align

公式

#include <iostream>
#include<cstdio>
#include<algorithm>
typedef long long ll;
using namespace std;

ll a[100005];

int main()
{
    ll n;scanf("%lld",&n);
    for(ll i=1;i<=n;i++) scanf("%lld",&a[i]);
    if(n==1){
        printf("0
");
        return 0;
    }
    sort(a+1,a+1+n);
    ll ans=0;
    if(n%2==0){
        ll num=(n-2)/2;
        ll tmp1=0;
        for(ll i=n;i>=n-num+1;i--) tmp1+=a[i];
        ll tmp2=0;
        for(ll i=1;i<=num;i++) tmp2+=a[i];
        ll tmp3=a[n-num]-a[num+1];
        ans=2*(tmp1-tmp2)+tmp3;
    }
    else{
        ll num=(n-1)/2;
        ll tmp1=0;
        for(ll i=n;i>=n-num+1;i--) tmp1+=a[i];
        ll tmp2=0;
        for(ll i=1;i<=num-1;i++) tmp2+=a[i];
        ll tmp3=a[num]+a[num+1];
        ll ans1=2*(tmp1-tmp2)-tmp3;
        tmp1=0,tmp2=0,tmp3=0;
        for(ll i=n;i>=n-num+2;i--) tmp1+=a[i];
        for(ll i=1;i<=num;i++) tmp2+=a[i];
        tmp3=a[num+1]+a[num+2];
        ll ans2=2*(tmp1-tmp2)+tmp3;
        ans=max(ans1,ans2);
    }
    printf("%lld
",ans);
    return 0;
}

C.Crossing

构造

#include <iostream>
#include<cstdio>
using namespace std;

bool ok[100005];

void init(){
  ok[1]=1,ok[2]=0,ok[3]=1;
  int now=3;
  for(int t=3;now+t<=100000;t++){
    ok[now+t]=1;
    now=now+t;
  }
}

int main()
{
    init();
    int n;scanf("%d",&n);
    if(ok[n]) puts("Yes");
    else puts("No");
    return 0;
}

B.滑动窗口

单调队列

#include <iostream>
#include<cstdio>
using namespace std;
 
int a[1000005],ans_max[1000005],ans_min[1000005],q[1000005];
 
int main()
{
    int n,k;scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++) scanf("%d",&a[i]);
    int head=1,tail=0;
    for(int i=1;i<=n;i++){
        while(head<=tail&&a[q[tail]]<=a[i]) tail--;
        q[++tail]=i;
        while(head<=tail&&i-q[head]+1>k) head++;
        ans_max[i]=a[q[head]];
    }
    head=1,tail=0;
    for(int i=1;i<=n;i++){
        while(head<=tail&&a[q[tail]]>=a[i]) tail--;
        q[++tail]=i;
        while(head<=tail&&i-q[head]+1>k) head++;
        ans_min[i]=a[q[head]];
    }
    for(int i=k;i<=n;i++){
        if(i!=k) printf(" ");
        printf("%d",ans_min[i]);
    }
    puts("");
    for(int i=k;i<=n;i++){
        if(i!=k) printf(" ");
        printf("%d",ans_max[i]);
    }
    puts("");
    return 0;
}

C.发财兔fbi树

dfs

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
 
char s[2005];
 
int dfs(int l,int r){
  if(l==r){
    if(s[l]=='0') {printf("B");return 0;}
    else {printf("I");return 1;}
  }
  int mid=(l+r)>>1;
  int tl=dfs(l,mid);
  int tr=dfs(mid+1,r);
  if(tl!=tr) {printf("F");return 2;}
  else{
    if(tl==0) {printf("B"); return 0;}
    else if(tl==1) {printf("I"); return 1;}
    else {printf("F"); return 2;}
  }
}
 
int main()
{
    int n;scanf("%d",&n);
    scanf("%s",s+1);
    n=strlen(s+1);
    int t=dfs(1,n);
    puts("");
    return 0;
}

D.医院设置

暴力+LCA

#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#define inf 0x3f3f3f3f3f3f3f3f
typedef long long ll;
using namespace std;
 
ll num[105],pre[105],depth[105],fa[105][105];
 
int main()
{
    ll n;scanf("%lld",&n);
    for(ll i=1;i<=n;i++){
        ll l,r;scanf("%lld%lld%lld",&num[i],&l,&r);
        pre[l]=i,pre[r]=i;
    }
    depth[1]=0;
    for(ll i=2;i<=n;i++){
        ll x=i;
        while(x!=1){
            depth[i]++;
            x=pre[x];
        }
    }
    for(ll i=1;i<=n;i++){
        for(ll j=1;j<=n;j++){
            ll x=i,y=j;
            while(depth[x]>depth[y]) x=pre[x];
            while(depth[y]>depth[x]) y=pre[y];
            while(x!=y){
                x=pre[x];
                y=pre[y];
            }
            fa[i][j]=x;
        }
    }
    ll ans=inf;
    for(ll i=1;i<=n;i++){
        ll tot=0;
        for(ll j=1;j<=n;j++){
            ll f=fa[i][j];
            ll l=depth[i]+depth[j]-2*depth[f];
            tot+=l*num[j];
        }
        ans=min(ans,tot);
    }
    printf("%lld
",ans);
    return 0;
}

E.加分二叉树

dp

#include <iostream>
#include<cstdio>
typedef long long ll;
using namespace std;

ll a[35],dp[35][35],ans[35][35];

ll DP(ll l,ll r){
   if(l>r) return 1;
   else if(l==r) return dp[l][r]=a[l];
   else{
    if(dp[l][r]) return dp[l][r];
    for(ll i=l;i<=r;i++){
        ll tmp=DP(l,i-1)*DP(i+1,r)+a[i];
        if(tmp>dp[l][r]){
            dp[l][r]=tmp;
            ans[l][r]=i;
        }
    }
    return dp[l][r];
   }
}

void print(ll l,ll r){
  if(l>r) return;
  else if(l==r) printf(" %lld",l);
  else{
    printf(" %lld",ans[l][r]);
    print(l,ans[l][r]-1);
    print(ans[l][r]+1,r);
  }
}

int main()
{
    ll n;scanf("%lld",&n);
    for(ll i=1;i<=n;i++) scanf("%lld",&a[i]);
    printf("%lld
",DP(1,n));
    printf("%lld",ans[1][n]);
    print(1,ans[1][n]-1);
    print(ans[1][n]+1,n);
    return 0;
}