Submission #42719680

---

Source Code Expand

/*+Rainybunny+*/

#include <bits/stdc++.h>

#define rep(i, l, r) for (int i = l, rep##i = r; i <= rep##i; ++i)
#define per(i, r, l) for (int i = r, per##i = l; i >= per##i; --i)

typedef std::pair<int, int> PII;
#define fi first
#define se second

const int MAXN = 1e3;
int n, p[MAXN + 5];
std::vector<PII> ans;

int main() {
    scanf("%d", &n);
    rep (i, 1, n) scanf("%d", &p[i]);

    int cnt = 0;
    rep (i, 1, n) rep (j, i + 1, n) cnt += p[j] < p[i];
    if (cnt & 1) return puts("No"), 0;

    rep (i, 1, n - 1) {
        int x = std::find(p + 1, p + n + 1, i) - p;
        if (x == n) {
            ans.emplace_back(n - 2, n - 2);
            p[n] = p[n - 1], p[n - 1] = p[n - 2], p[n - 2] = i, x = n - 2;
        }
        if (x != i) {
            ans.emplace_back(x, i - 1);
            int y = p[x + 1];
            per (j, x - 1, i) p[j + 2] = p[j];
            p[i] = i, p[i + 1] = y;
        }
    }

    puts("Yes");
    printf("%zd\n", ans.size());
    for (auto [i, j]: ans) printf("%d %d\n", i, j);
    // rep (i, 1, n) printf("%d%c", p[i], "\n "[i < n]);
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:17:10: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   17 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
./Main.cpp:18:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   18 |     rep (i, 1, n) scanf("%d", &p[i]);
      |                   ~~~~~^~~~~~~~~~~~~

Judge Result