new file: P15823.cpp

P15823.cpp

@@ -0,0 +1,48 @@
+#include<bits/stdc++.h>
+using namespace std;
+int n, p, q;
+int a[2005];
+int f[2005][2005];
+bool check(int w) {
+    for(int i = 0; i <= p; ++i) {
+        for(int j = 1; j <= n; ++j) {
+            f[i][j] = 0x7f7f7f7f;
+        }
+    }
+    for(int i = 1; i <= n; ++i) {
+        int s = upper_bound(a + 1, a + n + 1, a[i] - w) - a - 1;
+        int t = upper_bound(a + 1, a + n + 1, a[i] - 2 * w) - a - 1;
+        f[0][i] = f[0][t] + 1;
+        for(int j = 1; j <= p; ++j) {
+            f[j][i] = min(f[j - 1][s], f[j][t] + 1);
+        }
+    }
+    return f[p][n] <= q;
+}
+int main() {
+    scanf("%d%d%d", &n, &p, &q);
+    for (int i = 1; i <= n; ++i)
+    {
+        scanf("%d", &a[i]);
+    }
+    if (p + q >= n)
+    { // 若总数足够多，一个盯一个即可，固以下计算 p + q < 2000
+        printf("1\n");
+        return 0;
+    }
+    sort(a + 1, a + n + 1);
+    int l = 1, r = 1e9;
+    while(l < r) {
+        int mid = l + (r - l) / 2;
+        if(check(mid)) r = mid;
+        else l = mid + 1;
+    }
+    printf("%d\n", l);
+    return 0;
+}
+/*
+f i, k为仅用 i 个小区间处理完前 k 个点所用最少的大区间个数。
+
+
+f{i, k} = min(f{i − 1, s}, f{i, t} + 1)
+*/