rains

LevelupProblemByPrateekBhaiya/ArrayAndVector/6Rains.cpp

@@ -0,0 +1,46 @@
+/*
+Given n non-negative integers representing an elevation
+map where the width of each bar is 1,compute how much
+water it can trap after raining.
+INPUT
+[0,1,0,2,1,0,1,3,2,1,2,1]
+OUTPUT
+6
+T.C
+o(n)
+*/
+#include <iostream>
+#include <vector>
+using namespace std;
+int trappedWater(vector<int> heights)
+{
+    int water = 0;
+    // base case
+    int n = heights.size();
+    if (n <= 2)
+    {
+        return 0;
+    }
+    // Left max, Right Max
+    vector<int> left(n, 0), right(n, 0);
+    left[0] = heights[0];
+    right[n - 1] = heights[n - 1];
+    for (int i = 1; i < n; i++)
+    {
+        left[i] = max(left[i - 1], heights[i]);
+        right[n - i - 1] = max(right[n - i], heights[n - i - 1]);
+    }
+    // water
+    for (int i = 0; i < n; i++)
+    {
+        water += min(left[i], right[i]) - heights[i];
+    }
+
+    return water;
+}
+int main()
+{
+    vector<int> water = {0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1};
+    cout << trappedWater(water) << endl;
+    return 0;
+}