Implement trapped water calculation algorithm

Author: gauravbisen1

src/main/java/com/thealgorithms/searches/trapingeainwatter.java

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+public class trappedWater{
+ public static int trappedWater(int height[]){
+ int n = height.length;
+
+ //calculate left max boundary - array
+ int leftMax[] = new int[n];
+ leftMax[0] = height[0];
+ for (int i = 1; i < n; i++) {
+ leftMax[i] = Math.max(height[i], leftMax[i-1]);
+ }
+
+ //calculate right max boundary - array
+ int rightMax[] = new int[n];
+ rightMax[n-1] = height[n-1];
+ for (int i = n-2; i >= 0; i--) {
+ rightMax[i] = Math.max(height[i], rightMax[i+1]);
+ }
+
+ int trappedWater = 0;
+ //loop ->
+ for (int i = 0; i < n; i++) {
+ //water level = min(leftMaxBoundary , rightMaxBoundary)
+ int waterlevel = Math.min(leftMax[i], rightMax[i]);
+ //trappedWater = waterlevel - height[i]
+ trappedWater = trappedWater + waterlevel - height[i];
+ }
+ return trappedWater;
+ }
+ public static void main(String[] args) {
+ int height[] = {4,2,0,6,3,2,5};
+ System.out.println(trappedWater(height));
+ }
+}