题意：题目是中文的：http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=16216
分析：这道题目作为模板题其实值得多练习几次的。用树状数组来写：
View Code
1 #include <stdio.h> 2 #include <iostream> 3 using namespace std; 4 #define DEBUG 5 const int MAXN = 50000 + 10; 6 int a[MAXN], n; 7 int lowbit(int x){return x&(-x);} 8 int sum(int x){ 9 int ret=0; 10 while(x>0){ 11 ret+=a[x]; 12 x-=lowbit(x); 13 } 14 return ret; 15 } 16 void add(int x, int d){ 17 while(x<=n){ 18 a[x]+=d; 19 x+=lowbit(x); 20 } 21 } 22 int main(){ 23 #ifndef DEBUG 24 freopen("in.txt", "r", stdin); 25 #endif 26 int T, cas=1; 27 scanf("%d", &T); 28 while(T--){ 29 memset(a, 0, sizeof(a)); 30 scanf("%d", &n); 31 int i, x; 32 for(i=1; i<=n; i++){ 33 scanf("%d", &x); 34 add(i, x); 35 } 36 char cmd[10]; 37 printf("Case %d:\n", cas++); 38 while(scanf("%s", cmd) && cmd[0]!='E'){ 39 int a, b; 40 scanf("%d%d", &a, &b); 41 if(cmd[0]=='A') add(a, b); 42 else if(cmd[0]=='S') add(a, -b); 43 else if(cmd[0]=='Q') printf("%d\n", sum(b)-sum(a-1)); 44 } 45 } 46 return 0; 47 }
用线段树（点树）也是ok的：
View Code
1 #include <stdio.h> 2 #include <iostream> 3 using namespace std; 4 #define DEBUG 5 const int MAXN = 50000 + 10; 6 int data[MAXN], n; 7 struct Node{ 8 int l, r, k; 9 }; 10 Node znode[4*MAXN]; 11 int zfun(int a, int b){return a+b;} 12 void build(int l, int r, int n){ 13 int mid=(l+r)>>1; 14 znode[n].l=l; 15 znode[n].r=r; 16 if(l==r) znode[n].k=data[l]; 17 else{ 18 build(l, mid, 2*n); 19 build(mid+1, r, 2*n+1); 20 znode[n].k=zfun(znode[2*n].k, znode[2*n+1].k); 21 } 22 } 23 int query(int l, int r, int n){ 24 int mid=(znode[n].l+znode[n].r)>>1; 25 if(znode[n].l==l && znode[n].r==r) return znode[n].k; 26 else{ 27 if(r<=mid) return query(l, r, 2*n); 28 else if(l>mid) return query(l, r, 2*n+1); 29 else return zfun(query(l, mid, 2*n), query(mid+1, r, 2*n+1)); 30 } 31 } 32 void add(int nid, int d, int n){ 33 int mid=(znode[n].l+znode[n].r)>>1; 34 if(znode[n].l==nid && znode[n].r==nid){ 35 znode[n].k+=d; 36 int newn=n/2; 37 while(newn>=1){ 38 znode[newn].k=zfun(znode[2*newn].k, znode[2*newn+1].k); 39 newn/=2; 40 } 41 }else{ 42 if(nid<=mid) add(nid, d, 2*n); 43 else if(nid>mid) add(nid, d, 2*n+1); 44 } 45 } 46 47 int main(){ 48 #ifndef DEBUG 49 freopen("in.txt", "r", stdin); 50 #endif 51 int T, cas=1; 52 scanf("%d", &T); 53 while(T--){ 54 memset(data, 0, sizeof(data)); 55 scanf("%d", &n); 56 int i, x; 57 for(i=1; i<=n; i++) scanf("%d", &data[i]); 58 build(1, n, 1); 59 char cmd[10]; 60 printf("Case %d:\n", cas++); 61 while(scanf("%s", cmd) && cmd[0]!='E'){ 62 int a, b; 63 scanf("%d%d", &a, &b); 64 if(cmd[0]=='A') add(a, b, 1); 65 else if(cmd[0]=='S') add(a, -b, 1); 66 else if(cmd[0]=='Q') printf("%d\n", query(a, b, 1)); 67 } 68 } 69 return 0; 70 }