42. Trapping Rain Water (java)

Author: bluesword12350

solution/0042.Trapping Rain Water/Solution.java

@@ -0,0 +1,18 @@
+class Solution {
+    public int trap(int[] height) {
+        if (height == null || height.length == 0) return 0;
+        int lx = 0, rx = height.length - 1, l = height[lx], r = height[rx], re = 0;
+        while (lx < rx) {
+            if (l < r) {
+                lx++;
+                if (height[lx] < l) re += l - height[lx];
+                else l = height[lx];
+            } else {
+                rx--;
+                if (height[rx] < r) re += r - height[rx];
+                else r = height[rx];
+            }
+        }
+        return re;
+    }
+}