Time: 1 ms (59.15%), Space: 49.1 MB (6.38%) - LeetHub

Author: MukulParasar

0042-trapping-rain-water/0042-trapping-rain-water.java

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+class Solution {
+    public int trap(int[] height) {
+        int[] left = new int[height.length];
+        int maxL = 0;
+        int[] right = new int[height.length];
+        int maxR = 0;
+        for (int i = 0; i < left.length; i++) {
+            maxL = Math.max(maxL, height[i]);
+            left[i] = maxL;
+        }
+        for (int i = right.length - 1; i >= 0; i--) {
+            maxR = Math.max(maxR, height[i]);
+            right[i] = maxR;
+        }
+        // calculate water trap
+        int water = 0;
+        for (int i = 0; i < height.length; i++) {
+            int min = Math.min(left[i], right[i]);
+            int currWater = min - height[i];
+            water = water + currWater;
+        }
+        return water;
+    }
+}