// shoes-dm_n2.cpp #include "shoes.h" #include <algorithm> using namespace std; vector<int> change(vector<int> v) { int n = (int)v.size() / 2; vector<int> cnt(n, 0); for(int i = 0; i < 2*n; i++) if(v[i] > 0) cnt[v[i] - 1]++; for(int i = 1; i < n; i++) cnt[i] += cnt[i-1]; vector<int> cntl = cnt, cntr = cnt; for(int i = 0; i < 2*n; i++) if(v[i] > 0) v[i] = (--cntr[v[i] - 1]) + 1; else v[i] = -((--cntl[-v[i] - 1]) + 1); return v; } long long count_swaps(vector<int> S) { S = change(S); long long ans = 0; for (int i = 0; i < S.size(); i += 2) { int pos = find(S.begin() + i, S.end(), -S[i]) - S.begin(); ans += pos - i - (S[i] < 0 ? 1 : 0); for (int j = pos; j >= i + 2; j--) { S[j] = S[j - 1]; } } return ans; }

shoes.cpp: In function 'long long int count_swaps(std::vector<int>)':
shoes.cpp:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0; i < S.size(); i += 2)
                     ~~^~~~~~~~~~