#include <bits/stdc++.h> using namespace std; #define REP(i,a,b) for (int i = (a); i <= (b); ++i) #define REPD(i,a,b) for (int i = (a); i >= (b); --i) #define FORI(i,n) REP(i,1,n) #define FOR(i,n) REP(i,0,int(n)-1) #define mp make_pair #define pb push_back #define pii pair<int,int> #define vi vector<int> #define ll long long #define SZ(x) int((x).size()) #define DBG(v) cerr << #v << " = " << (v) << endl; #define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++) #define fi first #define se second const int N = 1000100; int n; int a[N], b[N]; int main() { scanf("%d", &n); FORI(i,n) scanf("%d", &a[i]); FORI(i,n) b[a[i]] = i; int lo = b[n], hi = b[n]; ll res = 0; FORI(m,n) { if (m%2 == 0) { int pos = b[n-m/2]; lo = min(lo, pos); hi = max(hi, pos); } int k = hi-lo+1, rem = m-k; int lomin = max(lo-rem, 1); int himax = min(hi+rem, n); int lomax = himax-m+1; //printf("m=%d, k=%d, rem=%d, lomin=%d, himax=%d, lomax=%d\n", m, k, rem, lomin,himax,lomax); if (rem>=0) res += lomax-lomin+1; } printf("%d %lld\n", 2*n+1, res); return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 | #include <bits/stdc++.h> using namespace std; #define REP(i,a,b) for (int i = (a); i <= (b); ++i) #define REPD(i,a,b) for (int i = (a); i >= (b); --i) #define FORI(i,n) REP(i,1,n) #define FOR(i,n) REP(i,0,int(n)-1) #define mp make_pair #define pb push_back #define pii pair<int,int> #define vi vector<int> #define ll long long #define SZ(x) int((x).size()) #define DBG(v) cerr << #v << " = " << (v) << endl; #define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++) #define fi first #define se second const int N = 1000100; int n; int a[N], b[N]; int main() { scanf("%d", &n); FORI(i,n) scanf("%d", &a[i]); FORI(i,n) b[a[i]] = i; int lo = b[n], hi = b[n]; ll res = 0; FORI(m,n) { if (m%2 == 0) { int pos = b[n-m/2]; lo = min(lo, pos); hi = max(hi, pos); } int k = hi-lo+1, rem = m-k; int lomin = max(lo-rem, 1); int himax = min(hi+rem, n); int lomax = himax-m+1; //printf("m=%d, k=%d, rem=%d, lomin=%d, himax=%d, lomax=%d\n", m, k, rem, lomin,himax,lomax); if (rem>=0) res += lomax-lomin+1; } printf("%d %lld\n", 2*n+1, res); return 0; } |