delete pics to save space

2.11212.cpp

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+//迭代加深搜索
+#include<cstdio>
+#include<cstring>
+using namespace std;
+const int maxn = 9;
+int n, a[maxn];
+//判断是否达到状态
+bool is_sorted() {
+  for(int i = 0; i < n-1; i++)
+    if(a[i] >= a[i+1]) return false;
+  return true;
+}
+//计算序列中不正确数的个数
+int h() {
+  int cnt = 0;
+  for(int i = 0; i < n-1; i++)
+    if(a[i]+1 != a[i+1]) cnt++;
+  if(a[n-1] != n) cnt++;
+  return cnt;
+}
+bool dfs(int d, int maxd) {
+  if(d*3 + h() > maxd*3) return false;//剪枝
+  if(is_sorted()) return true;
+  int b[maxn], olda[maxn];//辅助完成剪切，插入
+  memcpy(olda, a, sizeof(a));
+  //确定i，j区间
+  for(int i = 0; i < n; i++)
+   for(int j = i; j < n; j++) {
+     // cut
+     int cnt = 0;
+     for(int k = 0; k < n; k++)
+       if(k < i || k > j) b[cnt++] = a[k];//剪切
+
+     // insert before position k
+     for(int k = 0; k <= cnt; k++) {
+       int cnt2 = 0;
+       for(int p = 0; p < k; p++) a[cnt2++] = b[p];
+       for(int p = i; p <= j; p++) a[cnt2++] = olda[p];//插入
+       for(int p = k; p < cnt; p++) a[cnt2++] = b[p];
+
+       if(dfs(d+1, maxd)) return true;//递归搜索答案
+       memcpy(a, olda, sizeof(a));
+     }
+   }
+  return false;
+}
+
+int solve() {
+  if(is_sorted()) return 0;
+  int max_ans = 8;
+  //控制深度
+  for(int maxd = 1; maxd < max_ans; maxd++)
+    if(dfs(0, maxd)) return maxd;
+  return max_ans;//最坏情况
+}
+
+int main() {
+  int kase = 0;
+  while(scanf("%d", &n) == 1 && n) {
+    for(int i = 0; i < n; i++) scanf("%d", &a[i]);
+    printf("Case %d: %d\n", ++kase, solve());
+  }
+  return 0;
+}
+
+