A1 + X1 - X2 = G
A2 + X2 - X3 = G
.
.
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An + Xn - X1 = G
解得
X1 = X1
X2 = A1 - G + X1
X3 = A1 + A2 - G - G + X1
.
.
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Xn = sigma(1, n)A - n * G + X1
注意到ans = abs (X1 - lamda1) + abs (X2 - lamda2) + ... + abs (Xn - lamdan)
于是sort 取中位数
代码丑极了替换的
1 #include <cstdio> 2 #include <cstdlib> 3 #include <algorithm> 4 using namespace std; 5 const long long N = 2001000; 6 long long a[N], s[N], tar[N], n; 7 int main () 8 { 9 scanf ("%d", &n); 10 for (long long i = 1; i <= n; i ++) 11 scanf ("%d", &a[i]), s[i] = s[i - 1] + a[i]; 12 long long g = s[n] / n; 13 for (long long i = 1; i <= n; i ++) 14 tar[i] = i * g - s[i]; 15 sort (tar + 1, tar + 1 + n); 16 long long x = n >> 1, z (0); 17 for (long long i = 1; i <= n; i ++) 18 z += abs (tar[i] - tar[x]); 19 printf ("%lld\n", z); 20 return 0; 21 }