codeforces 111A/112C Petya and Inequiations

题目:Petya and Inequiations
传送门:

http://codeforces.com/problemset/problem/111/A

http://codeforces.com/problemset/problem/112/C

分析:
  先引一个简单的结论:“(a+b)^2>=a^2+b^2”,可得一个简单的贪心:让其中一个数越大越好;再从“a[1] + a[2] + ... + a[n] <= y”入手:让a[1]越大越好,a[2]、a[3]...a[n]都为1;如果这种构造方法不行,则无解。
代码:

#include<cstdio>
int main(){
    //freopen("in.txt","r",stdin);
    //freopen("out.txt","w",stdout);
    long long n,x,y;
    scanf("%I64d%I64d%I64d\n",&n,&x,&y);
    if(y<n || (y-n+1)*(y-n+1)+(n-1)<x)
        printf("-1\n");
    else{
        printf("%d\n",y-n+1);
        for(int i(2);i<=n;++i)printf("1\n");
    }
    //fclose(stdin);fclose(stdout);
    return 0;
} 

 

posted @ 2016-03-15 20:29  hjj1871984569  阅读(255)  评论(0编辑  收藏  举报