[luoguP1316] 丢瓶盖（二分答案）

Posted 2020-09-23 蒟蒻zht的博客

传送门

 

二分答案再判断即可

 

——代码

 1 #include <cstdio>
 2 #include <iostream>
 3 #include <algorithm>
 4 #define max(x, y) ((x) > (y) ? (x) : (y))
 5 #define N 1000001
 6 
 7 int n, m, ans, maxn;
 8 int a[N];
 9 
10 inline int read()
11 {
12     int x = 0, f = 1;
13     char ch = getchar();
14     for(; !isdigit(ch); ch = getchar()) if(ch == ‘-‘) f = -1;
15     for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - ‘0‘;
16     return x * f;
17 }
18 
19 inline bool check(int x)
20 {
21     int i, now = 1, sum = 1;
22     for(i = 1; i <= n; i++)
23         if(a[i] - a[now] >= x)
24         {
25             sum++;
26             now = i;
27         }
28     return sum >= m;
29 }
30 
31 int main()
32 {
33     int i, j, x, y, mid;
34     n = read();
35     m = read();
36     for(i = 1; i <= n; i++) a[i] = read(), maxn = max(a[i], maxn);
37     std::sort(a + 1, a + n + 1);
38     x = 1, y = maxn;
39     while(x <= y)
40     {
41         mid = (x + y) >> 1;
42         if(check(mid)) ans = mid, x = mid + 1;
43         else y = mid - 1;
44     }
45     printf("%d\n", ans);
46     return 0;
47 }

View Code