From 3a30051745f4bd76b27511bab08c4e0997dfc433 Mon Sep 17 00:00:00 2001
From: wisdompeak <guan.huifeng@gmail.com>
Date: Fri, 20 May 2022 23:33:14 -0700
Subject: [PATCH] Create 930.Binary-Subarrays-With-Sum_v2.cpp

---
 .../930.Binary-Subarrays-With-Sum_v2.cpp      | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 Hash/930.Binary-Subarrays-With-Sum/930.Binary-Subarrays-With-Sum_v2.cpp

diff --git a/Hash/930.Binary-Subarrays-With-Sum/930.Binary-Subarrays-With-Sum_v2.cpp b/Hash/930.Binary-Subarrays-With-Sum/930.Binary-Subarrays-With-Sum_v2.cpp
new file mode 100644
index 000000000..78bd1e41c
--- /dev/null
+++ b/Hash/930.Binary-Subarrays-With-Sum/930.Binary-Subarrays-With-Sum_v2.cpp
@@ -0,0 +1,34 @@
+class Solution {
+public:
+    int numSubarraysWithSum(vector<int>& A, int S) 
+    {       
+        int n = A.size();
+        vector<int>postZeros(n);
+        int count = 0;
+        for (int i=n-1; i>=0; i--)
+        {
+            postZeros[i] = count;
+            if (A[i]==0)            
+                count++;            
+            else
+                count = 0;
+        }
+        
+        int j = 0, sum = 0;
+        int ret = 0;
+        for (int i=0; i<n; i++)
+        {
+            while (j<=i || (j<n && sum < S))
+            {
+                sum += A[j];
+                j++;
+            }
+            
+            if (sum==S)
+                ret += postZeros[j-1]+1;
+            sum -= A[i]; 
+        }
+        
+        return ret;        
+    }
+};