Codeforces 540B - School Marks (思维)

题意

小明在写作业。他的总分不能超过x，中位数不能低于y。现在给出他已经知道的成绩，问能不能达成目标。

思路

首先我们知道，对于给定的中位数y，我们往数组里添一个(y-1)和一个(y-100)对于本题来说是没有区别的。同理，添一个y和添一个(y+100)也是一样的。

所以我们就能得到这么一个贪心策略，在剩下的课程中，如果当前的剩余分数够y，就放y，否则就放1。最后检查一下中位数看是不是符合条件。

我是先统一放上1，然后放上(y-1)，所以代码看起来有点麻烦。。

代码

#include <stack>#include <cstdio>#include <list>#include <cassert>#include <set>#include <fstream>#include <iostream>#include <string>#include <vector>#include <queue>#include <functional>#include <cstring>#include <algorithm>#include <cctype>#include <string>#include <map>#include <cmath>#include <ext/pb_ds/assoc_container.hpp>#include <ext/pb_ds/hash_policy.hpp>using namespace std;#define LL long long#define ULL unsigned long long#define SZ(x) (int)x.size()#define Lowbit(x) ((x) & (-x))#define MP(a, b) make_pair(a, b)#define MS(arr, num) memset(arr, num, sizeof(arr))#define PB push_back#define X first#define Y second#define ROP freopen("input.txt", "r", stdin);#define MID(a, b) (a + ((b - a) >> 1))#define LC rt << 1, l, mid#define RC rt << 1|1, mid + 1, r#define LRT rt << 1#define RRT rt << 1|1#define FOR(i, a, b) for ((i)=(a); (i) < (b); (i)++)const double PI = acos(-1.0);const int INF = 0x3f3f3f3f;const double eps = 1e-8;const int MAXN = 1000+10;const int MOD = 1e9;const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };const int seed = 131;int cases = 0;typedef pair<int, int> pii;int arr[MAXN];int main(){    //ROP;    vector<int> ans;    int n, k, p, x, y;    cin >> n >> k >> p >> x >> y;    int cur_score = 0;    for (int i = 1; i <= k; i++)    {        scanf("%d", &arr[i]);        cur_score += arr[i];    }    int rem_score = min((n-k)*p, x-cur_score), pos = k;    sort(arr+1, arr+1+k);    int mid_pos = (n+1)/2;    rem_score -= (n-k);    for (int i = k+1; i <= n; i++) arr[i] = 1;    if (rem_score < 0) { puts("-1"); return 0; }    y--;    for (int i = k+1; i <= n; i++)    {        if (rem_score >= y) arr[i] += y, rem_score -= y;        else if (rem_score > 0)            arr[i] += rem_score, rem_score = 0;        ans.PB(arr[i]);    }    sort(arr+1, arr+n+1);    if (arr[mid_pos] >= ++y)        for (auto i : ans) printf("%d ", i);    else puts("-1");    return 0;}