仅支持单点修改的可持久化线段树（未验证正确性）

Persistent-Segment-Tree(Sum).cpp

@@ -0,0 +1,121 @@
+#include <cstdio>
+
+#define ELEMENT_COUNT 100000
+#define EDITION_COUNT 100000
+
+using namespace std;
+
+struct node
+{
+	int l, r, sum;
+	node *lch, *rch;
+}*root[EDITION_COUNT];
+
+int n, d[ELEMENT_COUNT], hs = 0;
+
+void build(int l, int r, node *u)
+{
+	u->l = l;
+	u->r = r;
+	if (l == r)
+	{
+		u->sum = d[l];
+	}
+	else
+	{
+		int mid = (l + r) >> 1;
+		build(l, mid, u->lch = new node);
+		build(mid + 1, r, u->rch = new node);
+		u->sum = u->lch->sum + u->rch->sum;
+	}
+}
+
+int query(int l, int r, node *u)
+{
+	if (u->l == l && u->r == r)
+	{
+		return u->sum;
+	}
+	else
+	{
+		int mid = (u->l + u->r) >> 1;
+		if (r <= mid)
+		{
+			return query(l, r, u->lch);
+		}
+		else if (l > mid)
+		{
+			return query(l, r, u->rch);
+		}
+		else
+		{
+			return query(l, mid, u->lch) + query(mid + 1, r, u->rch);
+		}
+	}
+}
+
+void modify(int k, int v, node *u, node *ori)
+{
+	u->l = ori->l;
+	u->r = ori->r;
+	if (u->l == u->r)
+	{
+		u->sum = v;
+	}
+	else
+	{
+		int mid = (u->l + u->r) >> 1;
+		if (k <= mid)
+		{
+			u->rch = ori->rch;
+			u->lch = new node;
+			modify(k, v, u->lch, ori->lch);
+		}
+		else
+		{
+			u->lch = ori->lch;
+			u->rch = new node;
+			modify(k, v, u->rch, ori->rch);
+		}
+		u->sum = u->lch->sum + u->rch->sum;
+	}
+}
+
+int main()
+{
+	scanf("%d", &n);
+	for (int i = 1; i <= n; i++)
+	{
+		scanf("%d", &d[i]);
+	}
+	build(1, n, root[0] = new node);
+	int in, edition, ql, qr, k, v;
+	while (true)
+	{
+		scanf("%d", &in);
+		if (in == 1)
+		{
+			scanf("%d%d%d", &edition, &ql, &qr);
+			printf("%d\n", query(ql, qr, root[edition]));
+		}
+		else if (in == 2)
+		{
+			scanf("%d%d", &k, &v);
+			hs++;
+			modify(k, v, root[hs] = new node, root[hs - 1]);
+		}
+		else if (in == 3)
+		{
+			printf("Current edition : %d\n", hs);
+		}
+		else if (in == 0)
+		{
+			return 0;
+		}
+		else
+		{
+			printf("No such command!\n");
+		}
+	}
+	return 0;
+}