Codeforces 584E Anton and Ira
我们把点分为三类, 向左走的, 向右走的, 不动的。
最完美的情况就是每个点没有走反方向。
每次我们挑选最右边的向右走的去把向左走的交换过来,这样能保证最优。
#include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mk make_pair #define PLL pair<LL, LL> #define PLI pair<LL, int> #define PII pair<int, int> #define SZ(x) ((int)x.size()) #define ull unsigned long long using namespace std; const int N = 2000 + 7; const int inf = 0x3f3f3f3f; const LL INF = 0x3f3f3f3f3f3f3f3f; const int mod = 1e9 + 7; const double eps = 1e-8; int n, cost, a[N], b[N], to[N]; vector<PII> ans; int main() { scanf("%d", &n); for(int i = 1; i <= n; i++) scanf("%d", &a[i]); for(int i = 1; i <= n; i++) scanf("%d", &b[i]), to[b[i]] = i; for(int i = n; i >= 1; i--) { if(to[a[i]] > i) { int pre = i; for(int j = i + 1; j <= n && to[a[pre]] != pre; j++) { if(to[a[j]] == j) continue; ans.push_back(mk(pre, j)); cost += abs(j - pre); swap(a[pre], a[j]); pre = j; } } } printf("%d\n", cost); printf("%d\n", SZ(ans)); for(auto& t : ans) printf("%d %d\n", t.fi, t.se); return 0; } /* */