各种板子

Posted 2021-01-09 lmjer

二分

 

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二维前缀和

垃圾炸弹

https://www.lydsy.com/JudgeOnline/problem.php?id=1218

代码

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

const int maxn=5050;

int sum[maxn][maxn];

int main(){
    int n,r;
    int x,y,w;
    scanf("%d%d",&n,&r);
    for (int i=1;i<=n;i++){
        scanf("%d%d%d",&x,&y,&w);
        sum[x+1][y+1]=w;
    }
    for (int i=1;i<=5001;i++) sum[1][i]=sum[1][i-1]+sum[1][i];
    for (int i=1;i<=5001;i++) sum[i][1]=sum[i-1][1]+sum[i][1];
    for (int i=2;i<=5001;i++){
        for (int j=2;j<=5001;j++){
            sum[i][j]=sum[i-1][j]+sum[i][j-1]+sum[i][j]-sum[i-1][j-1];
        }
    }

    int ans=0;
    for (int i=r;i<=5001;i++){
        for (int j=r;j<=5001;j++){
            ans=max(ans,sum[i][j]-sum[i-r][j]-sum[i][j-r]+sum[i-r][j-r]);
        }
    }
    printf("%d",ans);
return 0;
}

 

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前缀和

https://www.luogu.org/recordnew/show/11207133

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

typedef long long ll;

const int maxn=100000+10;

ll sum[maxn];

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

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快速幂

https://www.luogu.org/problemnew/show/P1226

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

typedef long long ll;
ll mod;

ll quickmod(ll a,ll b,ll mod){
   ll ans=1%mod;
   for (;b;b>>=1){
    if(b&1) ans=ans*a%mod;
    a=a*a%mod;
   }
   return ans%mod;
}

int main(){
    ll a,b;
    scanf("%lld%lld%lld",&a,&b,&mod);
    printf("%lld^%lld mod %lld=%lld",a,b,mod,quickmod(a,b,mod));
return 0;
}