题意:给定 n 条绳子,它们的长度分别为 ai,现在要从这些绳子中切出 m 条长度相同的绳子,求最长是多少。
析:其中就是一个二分的水题,但是有一个坑,那么就是最后输出不能四舍五入,只能向下取整。
代码如下:
#pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #include <iostream> #include <cstring> #include <set> #include <queue> #include <algorithm> #include <vector> #include <map> #include <cctype> #include <cmath> #include <stack> #include <sstream> #define debug() puts("++++"); #define gcd(a, b) __gcd(a, b) #define lson l,m,rt<<1 #define rson m+1,r,rt<<1|1 #define freopenr freopen("in.txt", "r", stdin) #define freopenw freopen("out.txt", "w", stdout) using namespace std; typedef long long LL; typedef unsigned long long ULL; typedef pair<int, int> P; const int INF = 0x3f3f3f3f; const double inf = 0x3f3f3f3f3f3f; const double PI = acos(-1.0); const double eps = 1e-8; const int maxn = 1e4 + 10; const int mod = 1e9 + 7; const int dr[] = {-1, 0, 1, 0}; const int dc[] = {0, 1, 0, -1}; const char *de[] = {"0000", "0001", "0010", "0011", "0100", "0101", "0110", "0111", "1000", "1001", "1010", "1011", "1100", "1101", "1110", "1111"}; int n, m; const int mon[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; const int monn[] = {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; inline bool is_in(int r, int c){ return r >= 0 && r < n && c >= 0 && c < m; } double a[maxn]; bool judge(double mid){ int ans = 0; for(int i = 0; i < n; ++i) ans += (int)(a[i] / mid); return ans >= m; } double solve(){ double l = 0, r = INF; for(int i = 0; i < 100; ++i){ double mid = (l+r) / 2.0; if(judge(mid)) l = mid; else r = mid; } return floor(l*100) / 100; } int main(){ while(scanf("%d %d", &n, &m) == 2){ for(int i = 0; i < n; ++i) scanf("%lf", a+i); printf("%.2f\n", solve()); } return 0; }