莫队
基本上没什么变化,推一下公式就可以了
#include <bits/stdc++.h> #define INF 0x3f3f3f3f #define full(a, b) memset(a, b, sizeof a) using namespace std; typedef long long ll; inline int lowbit(int x){ return x & (-x); } inline int read(){ int X = 0, w = 0; char ch = 0; while(!isdigit(ch)) { w |= ch == '-'; ch = getchar(); } while(isdigit(ch)) X = (X << 3) + (X << 1) + (ch ^ 48), ch = getchar(); return w ? -X : X; } inline ll gcd(ll a, ll b){ return b ? gcd(b, a % b) : a; } inline ll lcm(ll a, ll b){ return a / gcd(a, b) * b; } template<typename T> inline T max(T x, T y, T z){ return max(max(x, y), z); } template<typename T> inline T min(T x, T y, T z){ return min(min(x, y), z); } template<typename A, typename B, typename C> inline A fpow(A x, B p, C lyd){ A ans = 1; for(; p; p >>= 1, x = 1LL * x * x % lyd)if(p & 1)ans = 1LL * x * ans % lyd; return ans; } const int N = 50005; int n, m, t, a[N], freq[N]; ll p[N], q[N], ans; struct Query{ int l, r, id, block; bool operator < (const Query &rhs) const { return (block ^ rhs.block) ? l < rhs.l : (block & 1) ? r < rhs.r : r > rhs.r; } }query[N]; void add(int k){ freq[a[k]] ++; ans += freq[a[k]] - 1; } void remove(int k){ freq[a[k]] --; ans -= freq[a[k]]; } int main(){ //freopen("data.txt", "r", stdin); n = read(), m = read(); t = (int)sqrt(n); for(int i = 1; i <= n; i ++) a[i] = read(); for(int i = 1; i <= m; i ++){ query[i].l = read(), query[i].r = read(); query[i].id = i, query[i].block = (query[i].l - 1) / t + 1; } sort(query + 1, query + m + 1); int l = 1, r = 0; for(int i = 1; i <= m; i ++){ int curL = query[i].l, curR = query[i].r; while(l < curL) remove(l ++); while(r < curR) add(++ r); while(l > curL) add(-- l); while(r > curR) remove(r --); ll tmp = 1LL * (query[i].r - query[i].l + 1) * (query[i].r - query[i].l) / 2; if(!ans){ p[query[i].id] = 0; continue; } ll f = gcd(ans, tmp), y = ans; y /= f, tmp /= f; p[query[i].id] = y, q[query[i].id] = tmp; } for(int i = 1; i <= m; i ++){ if(!p[i]) printf("%lld/1\n", p[i]); else printf("%lld/%lld\n", p[i], q[i]); } return 0; }
来源:https://www.cnblogs.com/onionQAQ/p/10859593.html