1218: [HNOI2003]激光炸弹

#include<iostream>#include<cstdio>using namespace std;inline int read(){    int x=0,f=1;char ch=getchar();    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x*f;} int n,r,mx,my,ans,f[5005][5005];int main(){n=read();r=read();for(int i=1;i<=n;i++){int x=read(),y=read(),v=read();f[x+1][y+1]=v;mx=max(x+1,mx);my=max(y+1,my);}mx=min(mx+r,5001);my=min(my+r,5001);for(int i=1;i<=mx;i++)for(int j=1;j<=my;j++){f[i][j]+=f[i-1][j]+f[i][j-1]-f[i-1][j-1];if(i>=r&&j>=r)ans=max(ans,f[i][j]-f[i-r][j]-f[i][j-r]+f[i-r][j-r]);}printf("%d",ans);return 0;}