莫队
还是一道模板。。不过洛谷数据加强了,必须要奇偶性排序+吸氧才能过,BZOJ可以直接过的~
#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 int gcd(int a, int b){ return b ? gcd(b, a % b) : a; } inline int lcm(int a, int 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 = 500005; const int M = 1000005; int n, m, t, a[N], freq[M], ans, res[N]; 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]; inline void add(int k){ freq[a[k]] ++; if(freq[a[k]] == 1) ans ++; } inline void remove(int k){ freq[a[k]] --; if(freq[a[k]] == 0) ans --; } int main(){ n = read(); for(int i = 1; i <= n; i ++) a[i] = read(); m = read(); t = (int)sqrt(n); 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(l > curL) add(-- l); while(r < curR) add(++ r); while(r > curR) remove(r --); res[query[i].id] = ans; } for(int i = 1; i <= m; i ++){ printf("%d\n", res[i]); } return 0; }
来源:https://www.cnblogs.com/onionQAQ/p/10858389.html