Binary indexed trees

binary_indexed_trees/bit.cpp

@@ -0,0 +1,46 @@
+#include<iostream>
+#include<string>
+#include<vector>
+#include<sstream>
+#include<cstring>
+#include<cstdio>
+#include<cmath>
+#include<algorithm>
+#include<numeric>
+#include<map>
+#include<set>
+#include<queue>
+using namespace std ;
+int tree[200002];
+int MaxVal=200002;
+
+int read(int idx){
+    if(idx==0)return 0;
+	int sum = 0;
+	while (idx > 0){
+		sum += tree[idx];
+		idx -= (idx & -idx);
+	}
+	return sum;
+}
+
+void update(int idx ,int val){
+	while (idx <= MaxVal){
+		tree[idx] += val;
+		idx += (idx & -idx);
+	}
+}
+
+int main(){
+
+  memset(tree,0,sizeof(tree));
+	update(3,1);
+	update(4,1);
+	cout<<read(5)<<endl;
+	update(10,2);
+	update(8,3);
+	cout<<read(9)<<endl;
+
+    return 0;
+}
+

binary_indexed_trees/orders_spoj.cpp

@@ -0,0 +1,85 @@
+#include<iostream>
+#include<string>
+#include<vector>
+#include<sstream>
+#include<cmath>
+#include<algorithm>
+#include<numeric>
+#include<map>
+#include<set>
+#include<queue>
+using namespace std ;
+int tree[200002];
+int MaxVal=200001;
+
+int read(int idx){
+    if(idx==0)return 0;
+	int sum = 0;
+	while (idx > 0){
+		sum += tree[idx];
+		idx -= (idx & -idx);
+	}
+	return sum;
+}
+
+
+int get(int sum){
+    int idx=1<<17;
+    int ac=0;
+
+    while(idx!=0){     
+        if(ac+idx>MaxVal || tree[ac+idx]>= sum){
+            idx>>=1;
+        }else{
+            sum-=tree[ac+idx];
+            ac+=idx;
+            idx>>=1;    
+        }
+    }
+
+    return ac+1;
+}
+
+
+void update(int idx ,int val){
+	while (idx <= MaxVal){
+		tree[idx] += val;
+		idx += (idx & -idx);
+	}
+}
+
+int main(){
+
+    int tc;
+    scanf("%d",&tc);
+
+    while(tc--){
+        memset(tree,0,sizeof(tree));
+        int n;
+        scanf("%d",&n);
+        int c[n];
+
+        for(int i=0;i<n;i++)
+            scanf("%d",&c[i]);
+
+        for(int i=0;i<n;i++)
+            update(i+1,1);
+
+        int val=n;
+        int dev[n];
+        for(int i=n-1;i>=0;i--){
+            dev[i]=get(val-c[i]);
+            update(dev[i],-1);
+            val--;
+        }
+
+        for(int i=0;i<n;i++){
+            if(i!=n-1)printf("%d ",dev[i]);    
+            else printf("%d",dev[i]);
+        }
+
+        printf("\n");
+    }
+
+    return 0;
+}