Init

ACMOJ-2091.cpp

@@ -0,0 +1,199 @@
+#include <cstdio>
+#define unlikely(x) __builtin_expect(!!(x), 0)
+struct char_reader {
+  FILE *f;
+  char *buf, *p1, *p2;
+  int size;
+  char_reader(FILE *fin, int bufsize = 1 << 16) {
+    f = fin;
+    size = bufsize;
+    p1 = p2 = 0;
+    buf = new char[size];
+  }
+  ~char_reader() { delete[] buf; }
+  inline int operator()() {
+    return p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, size, f), p1 == p2)
+               ? EOF
+               : *p1++;
+  }
+};
+struct char_writer {
+  FILE *f;
+  char *buf, *p, *end;
+  int size;
+  char_writer(FILE *fout, int bufsize = 1 << 16) {
+    f = fout;
+    size = bufsize;
+    buf = new char[size];
+    p = buf;
+    end = buf + bufsize;
+  }
+  ~char_writer() {
+    fwrite(buf, p - buf, 1, f);
+    delete[] buf;
+  }
+  inline char operator()(char ch) {
+    if (unlikely(end == p)) {
+      fwrite(buf, end - buf, 1, f);
+      p = buf;
+    }
+    return *p++ = ch;
+  }
+};
+char_reader gch(stdin);
+char_writer wch(stdout);
+template <typename T>
+inline int read(T &t) {
+  bool f = false;
+  int ch;
+  while (ch = gch(), !((ch >= '0' && ch <= '9') || ch == '-')) {
+    if (ch == EOF) return 0;
+  }
+  t = 0;
+  if (ch == '-') f = true, ch = gch();
+  t = ch ^ 48;
+  while (ch = gch(), ch >= '0' && ch <= '9')
+    t = (t << 3) + (t << 1) + (ch ^ 48);
+  if (f) t = -t;
+  return 1;
+}
+inline int read(char &c) {
+  c = 0;
+  int ch;
+  while (ch = gch(), (ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t')) {
+    if (ch == EOF) return 0;
+  }
+  c = ch;
+  return 1;
+}
+inline int read(char *s) {
+  int ch;
+  while (ch = gch(), (ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t')) {
+    if (ch == EOF) return 0;
+  }
+  *s++ = ch;
+  while (ch = gch(),
+         !(ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t') && ch != EOF)
+    *s++ = ch;
+  *s++ = 0;
+  return 1;
+}
+inline int read(const char *s) { return read((char *)s); }
+inline int readline(char *s) {
+  int ch;
+  while (ch = gch(), (ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t')) {
+    if (ch == EOF) return 0;
+  }
+  *s++ = ch;
+  while (ch = gch(), !(ch == '\n' || ch == '\r') && ch != EOF) *s++ = ch;
+  *s++ = 0;
+  return 1;
+}
+inline int readline(const char *s) { return readline((char *)s); }
+template <typename T>
+inline void write(T t) {
+  int stk[20], cnt = 0;
+  if (t == 0) {
+    wch('0');
+    return;
+  }
+  if (t < 0) {
+    wch('-');
+    t = -t;
+  }
+  while (t > 0) {
+    stk[cnt++] = t % 10;
+    t /= 10;
+  }
+  while (cnt) wch(stk[--cnt] + '0');
+}
+inline void write(char t) { wch(t); }
+inline void write(char *s) {
+  while (*s) wch(*s++);
+}
+inline void write(const char *s) { write((char *)s); }
+#if __cplusplus >= 201103L
+template <typename T, typename... Args>
+inline int read(T &t, Args &...args) {
+  return read(t) + read(args...);
+}
+template <typename T, typename... Args>
+inline void write(T t, Args... args) {
+  write(t);
+  write(args...);
+}
+#else
+template <typename A_t, typename B_t>
+inline int read(A_t &a, B_t &b) {
+  return read(a) + read(b);
+}
+template <typename A_t, typename B_t, typename C_t>
+inline int read(A_t &a, B_t &b, C_t &c) {
+  return read(a) + read(b) + read(c);
+}
+template <typename A_t, typename B_t, typename C_t, typename D_t>
+inline int read(A_t &a, B_t &b, C_t &c, D_t &d) {
+  return read(a) + read(b) + read(c) + read(d);
+}
+template <typename A_t, typename B_t>
+inline void write(A_t a, B_t b) {
+  write(a);
+  write(b);
+}
+template <typename A_t, typename B_t, typename C_t>
+inline void write(A_t a, B_t b, C_t c) {
+  write(a);
+  write(b);
+  write(c);
+}
+template <typename A_t, typename B_t, typename C_t, typename D_t>
+inline void write(A_t a, B_t b, C_t c, D_t d) {
+  write(a);
+  write(b);
+  write(c);
+  write(d);
+}
+#endif
+#include <vector>
+using namespace std;
+
+typedef long long LL;
+const int kMaxN = 1000000 + 10;
+const int kMaxS = 1000 + 10;
+int n, tot[kMaxS];
+LL s[kMaxN], c[kMaxN], f[kMaxN];
+vector<int> stk[kMaxS];
+
+inline LL X(int i) { return c[i]; }
+inline LL Y(int i) { return f[i - 1] + s[i] * c[i] * c[i] - 2 * s[i] * c[i]; }
+inline double Slope(int i, int j) {
+  return (Y(i) - Y(j)) / double(X(i) - X(j));
+}
+inline LL Calc(int i, int j) {
+  return f[j - 1] + s[i] * (c[i] - c[j] + 1) * (c[i] - c[j] + 1);
+}
+
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+#endif
+  read(n);
+  for (int i = 1; i <= n; ++i) {
+    read(s[i]);
+    c[i] = ++tot[s[i]];
+  }
+  for (int i = 1; i <= n; ++i) {
+    int t = s[i];
+    while (stk[t].size() >= 2 &&
+           Slope(stk[t][stk[t].size() - 2], i) >=
+               Slope(stk[t][stk[t].size() - 2], stk[t][stk[t].size() - 1]))
+      stk[t].pop_back();
+    stk[t].push_back(i);
+    while (stk[t].size() >= 2 && Calc(i, stk[t][stk[t].size() - 1]) <=
+                                     Calc(i, stk[t][stk[t].size() - 2]))
+      stk[t].pop_back();
+    f[i] = Calc(i, stk[t][stk[t].size() - 1]);
+  }
+  write(f[n], '\n');
+  return 0;
+}