Arrays

Trapping Rain water problem

RainWaterTrapping.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+
+//Time Complexity O(n)
+//Space Complexity O(n)
+int trappingWater(int arr[], int n){
+        int maxLeft[n],maxRight[n],level=0,water[n];
+
+        maxLeft[0]=arr[0];
+        for(int i=1;i<n;i++)
+        maxLeft[i]=max(arr[i],maxLeft[i-1]);//finds maximum height to left of block
+
+        maxRight[n-1]=arr[n-1];
+        for(int i=n-2;i>=0;i--)
+        maxRight[i]=max(arr[i],maxRight[i+1]);//finds maximum height to right of block
+
+        for(int i=0;i<n;i++) {
+        water[i]=abs(min(maxLeft[i],maxRight[i])-arr[i]);//minimum of maximum height-height of block=level of water stored above each building
+        level+=water[i];
+        }
+        return level; 
+    }
+
+int main()
+{
+    int n;
+    cin>>n;
+    int a[n];
+    for(int i=0;i<n;i++)
+    cin>>a[i];
+    int result=trappingWater(a,n);
+    cout<<result<<endl;
+}