Segment Trees

Author: amitbansal7

15.Segment Tree/RangeMinQuery.cpp

@@ -0,0 +1,85 @@
+/* Amit Bansal - @amitbansal7 */
+#include <bits/stdc++.h>
+#include <string>
+#define lli long long int
+#define llu unsigned long long int
+#define S(x) scanf("%d",&x)
+#define Sl(x) scanf("%lld",&x)
+#define Mset(p,i) memset(p,i,sizeof(p))
+#define mlc(t,n) (t *)malloc(sizeof(t)*n)
+#define NIL -1
+#define INF INT_MAX
+#define TC int testcase; S(testcase); while(testcase--)
+#define Pi 3.14159
+using namespace std;
+
+void UpdateQuery(int STree[],int low,int high,int pos,int newv,int v)
+{
+	if(low == high)
+	{
+		STree[pos] = newv;
+		return;
+	}
+
+	int mid = (low+high) >> 1;
+	if(v <= mid)
+		UpdateQuery(STree,low,mid,2*pos+1,newv,v);
+
+	else
+		UpdateQuery(STree,mid+1,high,2*pos+2,newv,v);
+
+	STree[pos] = min(STree[pos*2+1],STree[pos*2+2]);
+}
+
+int RangeMinQuery(int STree[],int qlow,int qhigh,int low,int high,int pos)
+{
+	if(qlow <= low && qhigh >= high)
+		return STree[pos];
+
+	if(qlow > high || qhigh < low)
+		return INT_MAX;
+
+	int mid = (low+high)>>1;
+
+	return min(RangeMinQuery(STree,qlow,qhigh,low,mid,2*pos+1),
+			   RangeMinQuery(STree,qlow,qhigh,mid+1,high,2*pos+2));
+}
+
+void BulidTree(int A[],int STree[],int low,int high,int pos)
+{
+	if(low == high)
+	{
+		STree[pos] = A[low];
+		return;
+	}
+	int mid = (low+high) >> 1;
+	BulidTree(A,STree,low,mid,2*pos+1);
+	BulidTree(A,STree,mid+1,high,2*pos+2);
+	STree[pos] = min(STree[2*pos+1],STree[2*pos+2]);
+}
+
+int main()
+{
+
+	int A[] = {-1,2,4,0};
+
+	int n = sizeof(A)/sizeof(A[0]);
+	int h = (int)(ceil(log2(n)));
+	int size = 2*(int)pow(2,h)-1;
+
+	int *STree  = mlc(int,size);
+
+	BulidTree(A,STree,0,n-1,0);
+
+	printf("%d\n",RangeMinQuery(STree,1,3,0,n-1,0));
+
+	UpdateQuery(STree,0,n-1,0,-3,1);
+	// new array -1,-3,4,0
+
+	printf("%d\n",RangeMinQuery(STree,1,3,0,n-1,0));
+
+
+
+
+	return 0;
+}

15.Segment Tree/RangeSumQuery.cpp

@@ -0,0 +1,81 @@
+/* Amit Bansal - @amitbansal7 */
+#include <bits/stdc++.h>
+#include <string>
+#define lli long long int
+#define llu unsigned long long int
+#define S(x) scanf("%d",&x)
+#define Sl(x) scanf("%lld",&x)
+#define Mset(p,i) memset(p,i,sizeof(p))
+#define mlc(t,n) (t *)malloc(sizeof(t)*n)
+#define NIL -1
+#define INF INT_MAX
+#define TC int testcase; S(testcase); while(testcase--)
+#define Pi 3.14159
+using namespace std;
+
+void updateQuery(int STree[],int low,int high,int pos,int val,int v)
+{
+	if(low == high)
+	{
+		STree[pos] = val;
+		return;
+	}
+	int mid = (low+high) >> 1;
+
+	if(v <= mid)
+		updateQuery(STree,low,mid,pos*2+1,val,v);
+	else
+		updateQuery(STree,mid+1,high,pos*2+2,val,v);
+
+	STree[pos] = STree[2*pos+1] + STree[2*pos+2];
+}
+
+int RangeSumQuery(int STree[],int qlow,int qhigh,int low,int high,int pos)
+{
+	if(low >= qlow && high <= qhigh)
+		return STree[pos];
+
+	if(low > qhigh || high < qlow)
+		return 0;
+
+	int mid = (low+high) >> 1;
+	return RangeSumQuery(STree,qlow,qhigh,low,mid,pos*2+1) +
+			   RangeSumQuery(STree,qlow,qhigh,mid+1,high,pos*2+2);
+
+}
+void BulidTree(int A[],int STree[],int low,int high,int pos)
+{
+	if(low == high)
+	{
+		STree[pos] = A[low];
+		return;
+	}
+
+	int mid = (low+high) >> 1;
+	BulidTree(A,STree,low,mid,pos*2+1);
+	BulidTree(A,STree,mid+1,high,pos*2+2);
+	STree[pos] = STree[pos*2+1] + STree[pos*2+2];
+
+}
+
+int main()
+{
+	int A[] = {1,4,3,5};
+
+	int n = sizeof(A)/sizeof(A[0]);
+	int h = (int)(ceil(log2(n)));
+	int size = 2*(int)pow(2,h)-1;
+
+	int *STree  = mlc(int,size);
+
+	BulidTree(A,STree,0,n-1,0);
+
+	printf("%d\n",RangeSumQuery(STree,1,2,0,n-1,0));
+
+	updateQuery(STree,0,n-1,0,8,2);
+	// new array 1,4,8,5
+
+	printf("%d\n",RangeSumQuery(STree,1,2,0,n-1,0));
+
+	return 0;
+}