[luoguP2862] [USACO06JAN]把牛Corral the Cows（二分 + 乱搞）

传送门

可以二分边长

然后另开两个数组，把x从小到大排序，把y从小到大排序

枚举x，可以得到正方形的长

枚举y，看看从这个y开始，往上能够到达多少个点，可以用类似队列来搞

其实发现算法的本质之后，x可以不用从小到大排序

#include <cstdio>
#include <iostream>
#include <algorithm>
#define N 1001
#define max(x, y) ((x) > (y) ? (x) : (y))int c, n, ans;
int x[N], y[N], a[N], b[N];inline int read()
{int x = 0, f = 1;char ch = getchar();for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = -1;for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - '0';return x * f;
}inline bool cmp1(int a, int b)
{return x[a] < x[b];
}inline bool cmp2(int a, int b)
{return y[a] < y[b];
}inline bool check(int len)
{int i, j, k, l, r, sum;for(i = 1; i <= n; i++){k = 1;sum = 0;l = x[a[i]];r = l + len - 1;for(j = 1; j <= n; j++){while(y[b[k]] - y[b[j]] + 1 <= len && k <= n){if(l <= x[b[k]] && x[b[k]] <= r) sum++;k++;}if(sum >= c) return 1;if(l <= x[b[j]] && x[b[j]] <= r) sum--;}}return 0;
}int main()
{int i, l = 1, r, mid;c = read();n = read();for(i = 1; i <= n; i++){x[i] = read();y[i] = read();r = max(r, x[i]);r = max(r, y[i]);a[i] = b[i] = i;}std::sort(a + 1, a + n + 1, cmp1);std::sort(b + 1, b + n + 1, cmp2);while(l <= r){mid = (l + r) >> 1;if(check(mid)) ans = mid, r = mid - 1;else l = mid + 1; }printf("%d\n", ans);return 0;
}

转载于:https://www.cnblogs.com/zhenghaotian/p/7506098.html

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