acm.hdu.edu.cn/showproblem.php?pid=1698
【AC】
1 #include<cstdio> 2 const int maxn=100005; 3 #define lson (i<<1) 4 #define rson (i<<1|1) 5 struct Seg 6 { 7 int l,r,lazy,val; 8 }tree[maxn<<2]; 9 int val[maxn]; 10 11 void push_up(int i) 12 { 13 tree[i].val=tree[lson].val+tree[rson].val; 14 } 15 16 void push_down(int i) 17 { 18 if (tree[i].lazy==-1) return; 19 tree[lson].lazy=tree[i].lazy; 20 tree[rson].lazy=tree[i].lazy; 21 tree[lson].val=tree[i].lazy*(tree[lson].r-tree[lson].l+1); 22 tree[rson].val=tree[i].lazy*(tree[rson].r-tree[rson].l+1); 23 tree[i].lazy=-1; 24 } 25 26 void build(int l,int r,int i=1) //build a segment tree of length n, and index 1..n 27 { 28 tree[i].l=l; 29 tree[i].r=r; 30 tree[i].lazy=-1; 31 if (l==r) tree[i].val=val[l]; 32 else 33 { 34 int mid=l+r>>1; 35 build(l,mid,lson); 36 build(mid+1,r,rson); 37 push_up(i); 38 } 39 } 40 41 void setval(int l,int r,int x,int i=1) 42 { 43 if (tree[i].l==l && tree[i].r==r) 44 { 45 tree[i].lazy=x; 46 tree[i].val=x*(r-l+1); 47 } 48 else 49 { 50 push_down(i); 51 int mid=tree[i].l+tree[i].r>>1; 52 if (r<=mid) setval(l,r,x,lson); 53 else if (l>mid) setval(l,r,x,rson); 54 else 55 { 56 setval(l,mid,x,lson); 57 setval(mid+1,r,x,rson); 58 } 59 push_up(i); 60 } 61 } 62 63 int query(int l,int r,int i=1) 64 { 65 if (tree[i].l==l && r==tree[i].r) return tree[i].val; 66 push_down(i); 67 int mid=tree[i].l+tree[i].r>>1; 68 if (r<=mid) return query(l,r,lson); 69 if (l>mid) return query(l,r,rson); 70 return query(l,mid,lson)+query(mid+1,r,rson); 71 } 72 73 int main() 74 { 75 int t; 76 scanf("%d",&t); 77 int cas=0; 78 while (t--) 79 { 80 int n; 81 scanf("%d",&n); 82 for (int i=1;i<=n;i++) val[i]=1; 83 build(1,n); 84 int m; 85 scanf("%d",&m); 86 for (int i=0;i<m;i++) 87 { 88 int l,r,k; 89 scanf("%d%d%d",&l,&r,&k); 90 setval(l,r,k); 91 } 92 printf("Case %d: The total value of the hook is %d. ",++cas,query(1,n)); 93 } 94 return 0; 95 }