Editorial for VM 12 Bài 18 - Đổi chỗ
Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.
Submitting an official solution before solving the problem yourself is a bannable offence.
Submitting an official solution before solving the problem yourself is a bannable offence.
Lưu ý: Các code mẫu dưới đây chỉ mang tính tham khảo và có thể không AC được bài tập này
Code mẫu của flashmt
#include <iostream> #include <algorithm> using namespace std; int brute(int a[],int n) { int best=0; for (int l=n-1;l;l--) for (int i=0;i+l<n;i++) { int j=i+l; if ((l-1)*2+1<=best) break; if (a[j]>a[i]) continue; int inc=0; for (int k=i+1;k<j;k++) { if (a[k]>a[i]) inc--; else inc++; if (a[k]<a[j]) inc--; else inc++; } best=max(best,inc+1); } return best; } int main() { int n,a[1000],inv=0; cin >> n; for (int i=0;i<n;i++) cin >> a[i]; for (int i=0;i<n;i++) for (int j=i+1;j<n;j++) inv+=a[i]>a[j]; cout << inv-brute(a,n) << endl; }
Code mẫu của ladpro98
program VMSWAP; uses math; const fi=''; maxn=1111; var f,g:array[1..maxn,0..maxn] of longint; a:array[1..maxn] of longint; n,i,j,res,s,t:longint; inp:text; begin assign(inp,fi);reset(inp); readln(inp,n); for i:=1 to n do read(inp,a[i]); for i:=1 to n do for j:=n downto 1 do if i>a[j] then f[i,j]:=f[i,j+1]+1 else f[i,j]:=f[i,j+1]; for i:=1 to n do for j:=1 to n do if a[j]>i then g[i,j]:=g[i,j-1]+1 else g[i,j]:=g[i,j-1]; for i:=1 to n do inc(s,f[a[i],i]); res:=s; for i:=1 to n-1 do for j:=i+1 to n do begin t:=s+f[a[i],j+1]+f[a[j],i+1]-f[a[i],i]-f[a[j],j]; t:=t+g[a[i],j]-g[a[i],i]-g[a[j],j]+g[a[j],i]; res:=min(res,t); end; write(res); end.
Code mẫu của RR
#include <sstream> #include <iomanip> #include <iostream> #include <cstdio> #include <cstring> #include <cstdlib> #include <cmath> #include <algorithm> #include <vector> #include <set> #include <map> #include <stack> #include <queue> #include <string> #include <deque> #include <complex> #define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++) #define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--) #define REP(i,a) for(int i=0,_a=(a); i<_a; i++) #define FORN(i,a,b) for(int i=(a),_b=(b);i<_b;i++) #define DOWN(i,a,b) for(int i=a,_b=(b);i>=_b;i--) #define SET(a,v) memset(a,v,sizeof(a)) #define sqr(x) ((x)*(x)) #define ll long long #define F first #define S second #define PB push_back #define MP make_pair #define DEBUG(x) cout << #x << " = "; cout << x << endl; #define PR(a,n) cout << #a << " = "; FOR(_,1,n) cout << a[_] << ' '; cout << endl; #define PR0(a,n) cout << #a << " = "; REP(_,n) cout << a[_] << ' '; cout << endl; using namespace std; //Buffer reading int INP,AM,REACHEOF; #define BUFSIZE (1<<12) char BUF[BUFSIZE+1], *inp=BUF; #define GETCHAR(INP) { \ if(!*inp) { \ if (REACHEOF) return 0;\ memset(BUF,0,sizeof BUF);\ int inpzzz = fread(BUF,1,BUFSIZE,stdin);\ if (inpzzz != BUFSIZE) REACHEOF = true;\ inp=BUF; \ } \ INP=*inp++; \ } #define DIG(a) (((a)>='0')&&((a)<='9')) #define GN(j) { \ AM=0;\ GETCHAR(INP); while(!DIG(INP) && INP!='-') GETCHAR(INP);\ if (INP=='-') {AM=1;GETCHAR(INP);} \ j=INP-'0'; GETCHAR(INP); \ while(DIG(INP)){j=10*j+(INP-'0');GETCHAR(INP);} \ if (AM) j=-j;\ } //End of buffer reading const long double PI = acos((long double) -1.0); int a[1011], n; int main() { scanf("%d", &n); FOR(i,1,n) scanf("%d", &a[i]); int inv = 0; FOR(i,1,n) FOR(j,i+1,n) if (a[i] > a[j]) ++inv; int best = inv; FORD(l,n-1,1) FOR(i,1,n-l) { int j = i + l; if (a[i] < a[j]) continue; if (inv - l - l + 1 >= best) continue; int cur = inv - 1; FOR(k,i+1,j-1) { if (a[k] < a[i] && a[k] > a[j]) cur -= 2; } best = min(best, cur); } cout << best << endl; return 0; }
Code mẫu của hieult
#include <set> #include <map> #include <list> #include <cmath> #include <ctime> #include <deque> #include <queue> #include <stack> #include <bitset> #include <cctype> #include <cstdio> #include <string> #include <vector> #include <cassert> #include <cstdlib> #include <cstring> #include <sstream> #include <iomanip> #include <iostream> #include <algorithm> using namespace std; typedef long long ll; typedef long double ld; typedef unsigned int ui; typedef unsigned long long ull; #define Rep(i,n) for(typeof(n) i = 0; i < (n); ++i) #define Repd(i,n) for(typeof(n) i = (n)-1; i >= 0; --i) #define For(i,a,b) for(typeof(b) i = (a); i <= (b); ++i) #define Ford(i,a,b) for(typeof(a) i = (a); i >= (b); --i) #define Fit(i,v) for(typeof((v).begin()) i = (v).begin(); i != (v).end(); ++i) #define Fitd(i,v) for(typeof((v).rbegin()) i = (v).rbegin(); i != (v).rend(); ++i) #define mp make_pair #define pb push_back #define fi first #define se second #define sz(a) ((int)(a).size()) #define all(a) (a).begin(), (a).end() #define ms(a,x) memset(a, x, sizeof(a)) #define nl puts("") #define sp printf(" ") #define ok puts("ok") template<class F, class T> T convert(F a, int p = -1) { stringstream ss; if (p >= 0) ss << fixed << setprecision(p); ss << a; T r; ss >> r; return r; } template<class T> void db(T a, int p = -1) { if (p >= 0) cout << fixed << setprecision(p); cout << a << " "; } template<class T> T gcd(T a, T b) { T r; while (b != 0) { r = a % b; a = b; b = r; } return a; } template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; } template<class T> T sqr(T x) { return x * x; } template<class T> T cube(T x) { return x * x * x; } template<class T> struct Triple { T x, y, z; Triple() {} Triple(T _x, T _y, T _z) : x(_x), y(_y), z(_z) {} }; template<class T> Triple<T> euclid(T a, T b) { if (b == 0) return Triple<T>(1, 0, a); Triple<T> r = euclid(b, a % b); return Triple<T>(r.y, r.x - a / b * r.y, r.z); } template<class T> int getbit(T s, int i) { return (s >> i) & 1; } template<class T> T onbit(T s, int i) { return s | (T(1) << i); } template<class T> T offbit(T s, int i) { return s & (~(T(1) << i)); } template<class T> int cntbit(T s) { return s == 0 ? 0 : cntbit(s >> 1) + (s & 1); } const int bfsz = 1 << 16; char bf[bfsz + 5]; int rsz = 0;int ptr = 0; char gc() { if (rsz <= 0) { ptr = 0; rsz = fread(bf, 1, bfsz, stdin); if (rsz <= 0) return EOF; } --rsz; return bf[ptr++]; } void ga(char &c) { c = EOF; while (!isalpha(c)) c = gc(); } int gs(char s[]) { int l = 0; char c = gc(); while (isspace(c)) c = gc(); while (c != EOF && !isspace(c)) { s[l++] = c; c = gc(); } s[l] = '\0'; return l; } template<class T> bool gi(T &v) { v = 0; char c = gc(); while (c != EOF && c != '-' && !isdigit(c)) c = gc(); if (c == EOF) return false; bool neg = c == '-'; if (neg) c = gc(); while (isdigit(c)) { v = v * 10 + c - '0'; c = gc(); } if (neg) v = -v; return true; } const double PI = 2 * acos(0); const string months[] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}; const int days[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int dr[] = {-1, 0, +1, 0}; const int dc[] = {0, +1, 0, -1}; const int inf = (int)1e9 + 5; const ll linf = (ll)1e16 + 5; const double eps = 1e-9; #define maxn 1005 int n, a[maxn], front_smaller[maxn][maxn], back_smaller[maxn][maxn], front_bigger[maxn][maxn], back_bigger[maxn][maxn]; int main() { // freopen("in.txt", "r", stdin); ms(front_smaller, 0); ms(back_smaller, 0); ms(front_bigger, 0); ms(back_bigger, 0); gi(n); For(i, 1, n) gi(a[i]); For(i, 1, n) { For(x, 1, n) { front_smaller[i][x] = front_smaller[i - 1][x]; front_bigger[i][x] = front_bigger[i - 1][x]; if (a[i] < x) ++front_smaller[i][x]; if (a[i] > x) ++front_bigger[i][x]; } } Ford(i, n, 1) { For(x, 1, n) { back_smaller[i][x] = back_smaller[i + 1][x]; back_bigger[i][x] = back_bigger[i + 1][x]; if (a[i] < x) ++back_smaller[i][x]; if (a[i] > x) ++back_bigger[i][x]; } } int res = 0; For(i, 1, n) res += back_smaller[i + 1][a[i]]; int original = res; For(i, 1, n - 1) For(j, i + 1, n) { int x = back_smaller[i + 1][a[i]] - back_smaller[j][a[i]]; int y = back_bigger[i + 1][a[i]] - back_bigger[j][a[i]]; int z = front_bigger[j - 1][a[j]] - front_bigger[i][a[j]]; int t = front_smaller[j - 1][a[j]] - front_smaller[i][a[j]]; int changes = original - x + y - z + t; if (a[i] > a[j]) --changes; else if (a[i] < a[j]) ++changes; res = min(res, changes); } printf("%d\n", res); return 0; }
Code mẫu của skyvn97
#include<cstdio> #define MAX 3030 int a[MAX]; int h[MAX][MAX]; int l[MAX][MAX]; int n; int fst,best; int min(const int &x,const int &y) { if (x<y) return (x); else return (y); } void init(void) { scanf("%d",&n); int i; for (i=1;i<=n;i=i+1) scanf("%d",&a[i]); } void count(void) { int i,j; fst=0; for (i=1;i<n;i=i+1) for (j=i+1;j<=n;j=j+1) fst=fst+(a[i]>a[j]); for (i=1;i<=n;i=i+1) { h[i][0]=0; l[i][0]=0; for (j=1;j<=n;j=j+1) { h[i][j]=h[i][j-1]+(a[j]>a[i]); l[i][j]=l[i][j-1]+(a[j]<a[i]); } } } void process(void) { best=fst; int i,j; for (i=1;i<n;i=i+1) for (j=i+1;j<=n;j=j+1) { best=min(best,fst+(h[i][j-1]-h[i][i])+(l[j][j-1]-l[j][i])-(l[i][j-1]-l[i][i])-(h[j][j-1]-h[j][i])-(a[i]>a[j])+(a[i]<a[j])); // printf("%d %d %d\n",i,j,best); } printf("%d",best); } int main(void) { init(); count(); process(); return 0; }
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