Yandex.Algorithm 2018, final round

思路:如果n这个位置加1的话,不同的数的个数要么不变,要么加1,反之,如果不同的数的个数减少,肯定不是n这个位置加1

我们random_shuffle()50次,每次把不是n的位置标记一下,这样有很大的概率把所有的不是n的位置都标记了

代码:

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize(4)
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pi acos(-1.0)
#define LL long long
//#define mp make_pair
#define pb push_back
#define ls rt<<1, l, m
#define rs rt<<1|1, m+1, r
#define ULL unsigned LL
#define pll pair<LL, LL>
#define pli pair<LL, int>
#define pii pair<int, int>
#define piii pair<pii, int>
#define mem(a, b) memset(a, b, sizeof(a))
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);
//head

const int N = 1e3 + 5;
int a[N];
bool vis[N];
int main() {
    int n, tot = 50;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++) a[i] = i;
    int pre = n, now;
    while(tot--) {
        random_shuffle(a+1, a+1+n);
        for (int i = 1; i <= n; i++) {
            printf("0 %d\n", a[i]);
            fflush(stdout);
            scanf("%d", &now);
            if(now < pre) {
                vis[a[i]] = true;
            }
            pre = now;
        }
    }
    for (int i = 1; i <= n; i++) if(!vis[i]) return 0*printf("1 %d\n", i);
    return 0;
}

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