[模板]树状数组
1.单点修改区间查询
OJ题号：洛谷P3374
1 #include<cstdio> 2 #include<cstring> 3 #define maxn 500000 4 int n,m; 5 struct BIT { 6 int val[maxn]; 7 BIT() { 8 memset(val,0,sizeof val); 9 } 10 int lowbit(int x) { 11 return x&-x; 12 } 13 void modify(int p,const int x) { 14 while(p<=n) { 15 val[p]+=x; 16 p+=lowbit(p); 17 } 18 } 19 int query(int p) { 20 int ans=0; 21 while(p) { 22 ans+=val[p]; 23 p-=lowbit(p); 24 } 25 return ans; 26 } 27 }; 28 BIT tree; 29 int main() { 30 scanf("%d%d",&n,&m); 31 for(int i=1;i<=n;i++) { 32 int x; 33 scanf("%d",&x); 34 tree.modify(i,x); 35 } 36 while(m--) { 37 int op,x,y; 38 scanf("%d%d%d",&op,&x,&y); 39 if(op==1) { 40 tree.modify(x,y); 41 } 42 else { 43 printf("%d\n",tree.query(y)-tree.query(x-1)); 44 } 45 } 46 return 0; 47 }
2.区间修改单点查询
OJ题号：洛谷P3368
1 #include<cstdio> 2 #include<cstring> 3 #define maxn 500001 4 int n,m,a[maxn]; 5 struct BIT { 6 int val[maxn]; 7 BIT() { 8 memset(val,0,sizeof val); 9 } 10 int lowbit(const int x) { 11 return x&-x; 12 } 13 void modify(int p,const int x) { 14 while(p) { 15 val[p]+=x; 16 p-=lowbit(p); 17 } 18 } 19 int query(int p) { 20 int ans=0; 21 while(p<=n) { 22 ans+=val[p]; 23 p+=lowbit(p); 24 } 25 return ans; 26 } 27 }; 28 BIT tree; 29 int main() { 30 scanf("%d%d",&n,&m); 31 for(int i=1;i<=n;i++) { 32 scanf("%d",&a[i]); 33 } 34 while(m--) { 35 int op; 36 scanf("%d",&op); 37 if(op==1) { 38 int x,y,k; 39 scanf("%d%d%d",&x,&y,&k); 40 tree.modify(y,k); 41 tree.modify(x-1,-k); 42 } 43 else { 44 int x; 45 scanf("%d",&x); 46 printf("%d\n",a[x]+tree.query(x)); 47 } 48 } 49 return 0; 50 }
