题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=3333
题意就是询问区间不同数字的和。
比较经典的树状数组应用。
1 //#pragma comment(linker, "/STACK:102400000, 102400000") 2 #include <algorithm> 3 #include <iostream> 4 #include <cstdlib> 5 #include <cstring> 6 #include <cstdio> 7 #include <vector> 8 #include <cmath> 9 #include <ctime> 10 #include <list> 11 #include <set> 12 #include <map> 13 using namespace std; 14 typedef long long LL; 15 typedef pair <int, int> P; 16 const int N = 1e5 + 5; 17 struct query { 18 int l, r, pos; 19 bool operator <(const query &cmp) const { 20 return r < cmp.r; 21 } 22 }q[N]; 23 int a[30005]; 24 LL bit[30005], ans[N]; 25 map <int, int> mp; 26 27 void update(int i, LL val) { 28 for( ; i <= 30000; i += (i&-i)) 29 bit[i] += val; 30 } 31 32 LL sum(int i) { 33 LL s = 0; 34 for( ; i >= 1; i -= (i&-i)) 35 s += (LL)bit[i]; 36 return s; 37 } 38 39 int main() 40 { 41 int t, n, m; 42 scanf("%d", &t); 43 while(t--) { 44 memset(bit, 0, sizeof(bit)); 45 mp.clear(); 46 scanf("%d", &n); 47 for(int i = 1; i <= n; ++i) { 48 scanf("%d", a + i); 49 } 50 scanf("%d", &m); 51 for(int i = 1; i <= m; ++i) { 52 scanf("%d %d", &q[i].l, &q[i].r); 53 q[i].pos = i; 54 } 55 sort(q + 1, q + m + 1); 56 int index = 1; 57 for(int i = 1; i <= n; ++i) { 58 if(mp.find(a[i]) != mp.end()) { //a[i]曾经出现过 59 update(mp[a[i]], (LL)-a[i]); 60 } 61 mp[a[i]] = i; 62 update(i, a[i]); 63 while(q[index].r == i && index <= m) { 64 ans[q[index].pos] = sum(q[index].r) - sum(q[index].l - 1); 65 ++index; 66 } 67 } 68 for(int i = 1; i <= m; ++i) { 69 printf("%lld ", ans[i]); 70 } 71 } 72 return 0; 73 }