【区间更新区间求和】HDU 1698 Just a Hook

acm.hdu.edu.cn/showproblem.php?pid=1698

【AC】

 #include<cstdio>
 const int maxn=;
 #define lson (i<<1)
 #define rson (i<<1|1)
 struct Seg
 {
     int l,r,lazy,val;
 }tree[maxn<<];
 int val[maxn];

 void push_up(int i)
 {
     tree[i].val=tree[lson].val+tree[rson].val;
 }

 void push_down(int i)
 {
     if (tree[i].lazy==-) return;
     tree[lson].lazy=tree[i].lazy;
     tree[rson].lazy=tree[i].lazy;
     tree[lson].val=tree[i].lazy*(tree[lson].r-tree[lson].l+);
     tree[rson].val=tree[i].lazy*(tree[rson].r-tree[rson].l+);
     tree[i].lazy=-;
 }

 void build(int l,int r,int i=)  //build a segment tree of length n, and index 1..n
 {
     tree[i].l=l;
     tree[i].r=r;
     tree[i].lazy=-;
     if (l==r) tree[i].val=val[l];
     else
     {
         int mid=l+r>>;
         build(l,mid,lson);
         build(mid+,r,rson);
         push_up(i);
     }
 }

 void setval(int l,int r,int x,int i=)
 {
     if (tree[i].l==l && tree[i].r==r)
     {
         tree[i].lazy=x;
         tree[i].val=x*(r-l+);
     }
     else
     {
         push_down(i);
         int mid=tree[i].l+tree[i].r>>;
         if (r<=mid) setval(l,r,x,lson);
         else if (l>mid) setval(l,r,x,rson);
         else
         {
             setval(l,mid,x,lson);
             setval(mid+,r,x,rson);
         }
         push_up(i);
     }
 }

 int query(int l,int r,int i=)
 {
     if (tree[i].l==l && r==tree[i].r) return tree[i].val;
     push_down(i);
     int mid=tree[i].l+tree[i].r>>;
     if (r<=mid) return query(l,r,lson);
     if (l>mid) return query(l,r,rson);
     return query(l,mid,lson)+query(mid+,r,rson);
 }

 int main()
 {
     int t;
     scanf("%d",&t);
     int cas=;
     while (t--)
     {
         int n;
         scanf("%d",&n);
         for (int i=;i<=n;i++) val[i]=;
         build(,n);
         int m;
         scanf("%d",&m);
         for (int i=;i<m;i++)
         {
             int l,r,k;
             scanf("%d%d%d",&l,&r,&k);
             setval(l,r,k);
         }
         printf("Case %d: The total value of the hook is %d.\n",++cas,query(,n));
     }
     return ;
 }