[Leetcode 42] Trapping Rain Water

Title Link: trapping-rain-water

Import java.util.stack;/** * Given n non-negative integers representing an elevation map where the width of each bar is 1, Compute how much water it was able to trap after raining. For example, Given [0,1,0,2,1,0,1,3,2,1,2,1], return 6.The above elevation map are represented by array [0,1,0,2,1,0,1,3,2, 1,2,1]. 6 units of rain Water (blue section) is being trapped. Thanks Marcos for contributing this image! * */public class Trappingrainwater {//Solution one//315/315 test Cases passed.//status:accepted//runtime:248 ms//submitted:0 minutes ago//Time complexity O (n), Space complexity O (1) public int trap (int[] A) {int sum = 0;//int ma          x = 0;     for (int i = 0; i < a.length; i++) {//Find maximum if (A[i] > A[max]) {max = i;}}        Calculates the left int topest = 0;         for (int i = 0; i < max; i++) {if (A[i] > topest) {topest = A[i];} else {sum + = Topest-a[i];}}        Calculate Right topest = 0; for (int i = a.length-1; i > max; i--) {if (A[i] > Topest) {topest = A[i];} else {sum + = Topest-a[i];}}        return sum;        }//Solution two//315/315 test Cases passed.//status:accepted//runtime:282 ms//submitted:1 minute ago Time complexity O (n) space complexity O (n) public int trap1 (int[] A) {stack<integer> Stack = new stack<integer> (); int sum = 0;int i = 0;int max = maximum value in the 0;//stack for (; i < a.length-1; i++) {//Find leftmost maximum if (A[i] > a[i + 1]) {Stack.add (a[i]); MA x = A[i];break;}} for (i = i + 1; i < a.length; i++) {int count = 1;while (!stack.isempty () && stack.peek () <= a[i]) {//if the top element of the stack Less than the current element if (A[i] >= max) {//If the current element is greater than or equal to the maximum value in the stack while (!stack.isempty ()) {//will stack all the elements out of the stack sum + = Max-stack.pop ();} max = a[i];//Sets the maximum value of the current stack} else {//If the current element is less than the maximum value in the stack = + a[i]-stack.pop () count++;//cumulative A[i] The number of times to go into the stack}}while (count! = 0) {stack. Add (A[i]); count--;}} return sum;} public static void Main (string[] args) {}}

[Leetcode 42] Trapping Rain Water