笛卡尔树的构建

Author: Dev-XYS

Cartesian-Tree.cpp

@@ -0,0 +1,80 @@
+#include <cstdio>
+#include <cstring>
+#include <algorithm>
+
+#define NIL 0
+
+using namespace std;
+
+struct data
+{
+	char id[100];
+	int pr;
+}d[50010];
+
+int n, lch[50010], rch[50010], S[50010], sp;
+
+inline void parse(char *buf, char *str, int *num)
+{
+	for (int i = 0; ; i++)
+	{
+		if (buf[i] == '/')
+		{
+			buf[i] = ' ';
+			break;
+		}
+	}
+	sscanf(buf, "%s %d", str, num);
+}
+
+void print_tree(int rt)
+{
+	if (rt != 0)
+	{
+		printf("(");
+		print_tree(lch[rt]);
+		printf("%s/%d", d[rt].id, d[rt].pr);
+		print_tree(rch[rt]);
+		printf(")");
+	}
+}
+
+inline bool _data_cmp_(const data &x, const data &y)
+{
+	return strcmp(x.id, y.id) < 0;
+}
+
+int main()
+{
+	char temp[1000];
+	while (true)
+	{
+		scanf("%d", &n);
+		if (n == 0)
+		{
+			break;
+		}
+		for (int i = 1; i <= n; i++)
+		{
+			scanf("%s", temp);
+			parse(temp, d[i].id, &d[i].pr);
+		}
+		sort(d + 1, d + n + 1, _data_cmp_);
+		sp = 0;
+		for (int i = 1; i <= n; i++)
+		{
+			lch[i] = rch[i] = NIL;
+			S[sp] = 0;
+			while (sp > 0 && d[i].pr > d[S[sp - 1]].pr) sp--;
+			if (sp > 0)
+			{
+				rch[S[sp - 1]] = i;
+			}
+			lch[i] = S[sp];
+			S[sp++] = i;
+		}
+		print_tree(S[0]);
+		printf("\n");
+	}
+	return 0;
+}