MooFest
高级数据结构p203
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <cmath> 5 #include <algorithm> 6 using namespace std; 7 #define LL long long 8 const int maxn = 20010; 9 10 LL dis[maxn], cnt[maxn]; 11 int n; 12 13 struct Cow{ 14 int v, p; 15 bool operator < (const Cow& a)const{ 16 return v < a.v; 17 } 18 }c[maxn]; 19 20 void init(){ 21 memset(dis, 0, sizeof dis); 22 memset(cnt, 0, sizeof cnt); 23 } 24 LL sum(int i, LL *c){ 25 LL res = 0; 26 for(; i; i -= i & -i) res += c[i]; 27 return res; 28 } 29 void add(int i, int v, LL *c){ 30 for(; i <= maxn; i += i & -i) c[i] += v; 31 } 32 int main(){ 33 while(scanf("%d", &n) != EOF){ 34 init(); 35 for(int i = 1; i <= n; i++){ 36 scanf("%d %d", &c[i].v, &c[i].p); 37 } 38 sort(c + 1, c + n + 1); 39 LL tot = 0, ans = 0; 40 for(int i = 1; i <= n; i++){ 41 LL cnt1 = sum(c[i].p, cnt), sum1 = sum(c[i].p, dis); 42 LL cnt2 = i - 1 - cnt1, sum2 = tot - sum1; 43 ans += c[i].v * (cnt1 * c[i].p - sum1 + sum2 - cnt2 * c[i].p); 44 tot += c[i].p; 45 add(c[i].p, c[i].p, dis); 46 add(c[i].p, 1, cnt); 47 } 48 printf("%lld ", ans); 49 } 50 return 0; 51 }