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[luoguP1103] 书本整理(DP)

传送门

 

以 去掉多少个 为阶段不好做。

去掉 k 个也可以变成选 n - k 个

f[i][j] 表示前 i 个数中 选 j 个的最优解,a[i] 必选

f[i][j] = min(f[i][j], f[k][j - 1] + abs(b[k] - b[i])) (2 <= j <= min(i, n - m), j - 1 <= k < i)

 

——代码

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 1 #include <cstdio> 2 #include <cstring> 3 #include <iostream> 4 #include <algorithm> 5  6 const int MAXN = 101, INF = ~(1 << 31); 7 int n, m, ans = INF; 8 int f[MAXN][MAXN]; 9 10 struct node11 {12     int a, b;13 }p[MAXN];14 15 inline int read()16 {17     int x = 0, f = 1;18     char ch = getchar();19     for(; !isdigit(ch); ch = getchar()) if(ch == -) f = -1;20     for(; isdigit(ch); ch = getchar()) x = (x << 1) + (x << 3) + ch - 0;21     return x * f;22 }23 24 inline bool cmp(node x, node y)25 {26     return x.a < y.a;27 }28 29 inline int min(int x, int y)30 {31     return x < y ? x : y;32 }33 34 inline int abs(int x)35 {36     return x < 0 ? -x : x;37 }38 39 int main()40 {41     int i, j, k;42     n = read();43     m = n - read();44     for(i = 1; i <= n; i++) p[i].a = read(), p[i].b = read();45     std::sort(p + 1, p + n + 1, cmp);46     for(i = 2; i <= n; i++)47         for(j = 2; j <= min(i, m); j++)48         {49             f[i][j] = INF;50             for(k = j - 1; k < i; k++)51                 f[i][j] = min(f[i][j], f[k][j - 1] + abs(p[k].b - p[i].b));52         }53     for(i = m; i <= n; i++) ans = min(ans, f[i][m]);54     printf("%d\n", ans);55     return 0;56 }
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[luoguP1103] 书本整理(DP)