20240418

ACMOJ-2178.cpp

@@ -0,0 +1,92 @@
+#include <algorithm>
+#include <cmath>
+#include <cstdio>
+#include <cstring>
+#include <iostream>
+using namespace std;
+typedef long long LL;
+typedef long double LDB;
+const int kMaxN = 310;
+char s[kMaxN];
+int N, M;
+int Calc1(int st) {
+  int target[20] = {0};
+  for (int i = 0; i < M; i++) target[i] = (st >> i) & 1;
+  int cost[kMaxN][2] = {0};
+  int bucket_tot = N / M;
+  int left = N % M;
+  int initial_cost = 0;
+  for (int i = 0; i < left; i++)
+    initial_cost += s[bucket_tot * M + i] != target[i] ? 1 : 0;
+  for (int i = 0; i < bucket_tot; i++) {
+    for (int j = 0; j < M; j++) {
+      if (s[i * M + j] == target[j])
+        cost[i][1]++;
+      else
+        cost[i][0]++;
+    }
+  }
+  int dp[kMaxN][2];
+  memset(dp, 0x3f, sizeof(dp));
+  dp[bucket_tot][0] = initial_cost;
+  for (int i = bucket_tot - 1; i >= 0; i--) {
+    dp[i][0] = min(dp[i + 1][0] + cost[i][0], dp[i + 1][1] + cost[i][0] + 1);
+    dp[i][1] = min(dp[i + 1][0] + cost[i][1] + 1, dp[i + 1][1] + cost[i][1]);
+  }
+  return min(dp[0][0], dp[0][1]);
+}
+void Case1() {
+  int res = 0x3f3f3f3f;
+  for (int i = 0; i < N; i++) s[i] = s[i] - '0';
+  for (int st = 0; st < (1 << M); st++) res = min(res, Calc1(st));
+  printf("%d\n", res);
+}
+int Calc2(int st) {
+  int bucket_tot = N / M;
+  int cur_status = 0, status = 0;
+  int tot = 0;
+  for (int i = bucket_tot - 1; i >= 0; i--) {
+    int cur = (st >> i) & 1;
+    tot += cur;
+    cur_status ^= cur;
+    status <<= 1;
+    status |= cur_status;
+  }
+  int S[kMaxN];
+  for (int i = 0; i < N; i++) {
+    S[i] = s[i] - '0';
+    int block_id = i / M;
+    int hat = (status >> block_id) & 1;
+    S[i] ^= hat;
+  }
+  for (int i = 0; i < M; i++) {
+    int cnt_one = 0;
+    int cnt_zero = 0;
+    for (int j = i; j < N; j += M) {
+      if (S[j] == 1)
+        cnt_one++;
+      else
+        cnt_zero++;
+    }
+    tot += min(cnt_one, cnt_zero);
+  }
+  return tot;
+}
+void Case2() {
+  int bucket_tot = N / M;
+  int res = 0x3f3f3f3f;
+  for (int st = 0; st < (1 << bucket_tot); st++) res = min(res, Calc2(st));
+  printf("%d\n", res);
+}
+int main() {
+#ifdef local
+  freopen("pro.in", "r", stdin);
+#endif
+  scanf("%s%d", s, &M);
+  N = strlen(s);
+  if (M <= sqrt(N))
+    Case1();
+  else
+    Case2();
+  return 0;
+}