BZOJ-3289 Mato的文件管理
用分块莫队离线询问的同时用树状数组快速计算逆序对个数。
#include <cstdlib> #include <cstdio> #include <cmath> #include <cstring> #include <algorithm> #include <fstream> #include <iostream> #include <queue> #define rep(i, l, r) for(int i = l; i <= r; i++) #define down(i, l, r) for(int i = l; i >= r; i--) #define N 56789 #define ll long long using namespace std; int read() { int x = 0, f = 1; char ch = getchar (); while (ch< '0' || ch> '9' ) { if (ch== '-' ) f = -1; ch = getchar (); } while (ch>= '0' && ch<= '9' ) { x = x*10 + ch- '0' ; ch = getchar (); } return x*f; } struct node{ int l, r, id;} q[N]; int n, m, k[N], a[N], pos[N], ans[N], s[N], now; bool cmp(node a, node b) { if (pos[a.l] == pos[b.l]) return a.r < b.r; else return a.l < b.l; } int Q( int x) { int a = 0; while (x>0) a+=s[x], x-=x&(-x); return a; } void Add( int x, int c) { while (x<=n) s[x]+=c, x+=x&(-x); } int main() { n=read(); rep(i, 1, n) k[i]=a[i]=read(); sort(a+1, a+1+n); rep(i, 1, n) k[i] = lower_bound(a+1, a+n+1, k[i])-a; int block = int ( sqrt (n)); rep(i, 1, n) pos[i] = (i-1)/block+1; m=read(); rep(i, 1, m) q[i].l=read(), q[i].r=read(), q[i].id = i; sort(q+1, q+1+m, cmp); int l = 1, r = 0; rep(i, 1, m) { while (l < q[i].l) now -= Q(k[l]-1), Add(k[l], -1), l++; while (l > q[i].l) l--, now += Q(k[l]-1), Add(k[l], 1); while (r < q[i].r) r++, now += r-l-Q(k[r]), Add(k[r], 1); while (r > q[i].r) now -= r-l+1-Q(k[r]), Add(k[r], -1), r--; ans[q[i].id] = now; } rep(i, 1, m) printf ( "%d\n" , ans[i]); return 0; } |
【推荐】编程新体验,更懂你的AI,立即体验豆包MarsCode编程助手
【推荐】凌霞软件回馈社区,博客园 & 1Panel & Halo 联合会员上线
【推荐】抖音旗下AI助手豆包,你的智能百科全书,全免费不限次数
【推荐】轻量又高性能的 SSH 工具 IShell:AI 加持,快人一步