算法训练 格子操作（线段树）-----------C语言—菜鸟级

#include<stdio.h> 
#define N 40000001
#define MAX(a,b) a>b?a:b
typedef struct node
{long int max,sum;
}L;
L node[N];
 
 void f(long int now,long int l,long int r, long int le,long int ri,long int s)//修改 或初始附值 
 {        if(r==ri&&l==le)
          { 
             node[now].sum=s;
             node[now].max=s;
          }
          else
          {
          	long int mid=(r+l)>>1;
          	long int next=now<<1;
          	if(ri<=mid)f(next,l,mid,le,ri,s);
          	else f(next+1,mid+1,r,le,ri,s);
          	node[now].sum=node[next].sum+node[next+1].sum;
          	node[now].max=MAX(node[next].max,node[next+1].max);
          }
 }

long int outsum(long int now,long int l,long int r ,long int le,long int ri)//求区间和 
{
	 if(r==ri&&l==le)return node[now].sum ;
	   else
	   {  long int mid=(r+l)>>1;
	   	  long int next=now<<1;
	   	  if(ri<=mid) return outsum(next,l,mid,le,ri);
	   	   else if(mid<le) return outsum(next+1,mid+1,r,le,ri);
	   	     else return outsum(next,l,mid,le,mid)+outsum(next+1,mid+1,r,mid+1,ri);
	   }
}
 long int outmax(long int now,long int l,long int r,long int le,long int ri)//求区间最大值 
 { long int M;
 	    if(r==ri&&l==le)M=node[now].max;
 	    else
 	    { long int mid=(r+l)>>1;
 	      long  int next=now<<1;
 	      if(ri<=mid)M=outmax(next,l,mid,le,ri);
 	      else if(le>mid)M=outmax(next+1,mid+1,r,le,ri);
 	      else M=MAX(outmax(next,l,mid,le,mid),outmax(next+1,mid+1,r,mid+1,ri));
 	    }
 	    
 	return M;
 	
 }
int main()
{
 long int n,i,s,m,p,x,y;
 scanf("%ld%ld",&n,&m);

 for(i=1;i<=n;i++)
 { scanf("%ld",&s);
   f(1,1,n,i,i,s);
 }
for(i=0;i<m;i++)
{  scanf("%ld%ld%ld",&p,&x,&y);
   if(p==1)f(1,1,n,x,x,y);
   if(p==2)printf("%ld\n",outsum(1,1,n,x,y));
   if(p==3)printf("%ld\n",outmax(1,1,n,x,y));
}
return 0;
}