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