From 5f650ab9fc90208ec2925eee4dfe35961ed25296 Mon Sep 17 00:00:00 2001
From: zhaocchen <zhaocchen@163.com>
Date: Sun, 18 Jul 2021 22:59:42 +0800
Subject: [PATCH] feat: add typescript solution to lc problem: No.0042.Trapping
 Rain Water

---
 .../0042.Trapping Rain Water/README.md        | 30 +++++++++++++++++++
 .../0042.Trapping Rain Water/README_EN.md     | 30 +++++++++++++++++++
 .../0042.Trapping Rain Water/Solution.ts      | 25 ++++++++++++++++
 3 files changed, 85 insertions(+)
 create mode 100644 solution/0000-0099/0042.Trapping Rain Water/Solution.ts

diff --git a/solution/0000-0099/0042.Trapping Rain Water/README.md b/solution/0000-0099/0042.Trapping Rain Water/README.md
index 5a666bb283351..3f84f971b3136 100644
--- a/solution/0000-0099/0042.Trapping Rain Water/README.md	
+++ b/solution/0000-0099/0042.Trapping Rain Water/README.md	
@@ -102,6 +102,36 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function trap(height: number[]): number {
+    let ans = 0;
+    let left = 0, right = height.length - 1;
+    let maxLeft = 0, maxRight = 0;
+    while (left < right) {
+        if (height[left] < height[right]) {
+            // move left
+            if (height[left] >= maxLeft) {
+                maxLeft = height[left];
+            } else {
+                ans += (maxLeft - height[left]);
+            }
+            ++left;
+        } else {
+            // move right
+            if (height[right] >= maxRight) {
+                maxRight = height[right];
+            } else {
+                ans += (maxRight - height[right]);
+            }
+            --right;
+        }
+    }
+    return ans;
+};
+```
+
 ### **C++**
 
 ```cpp
diff --git a/solution/0000-0099/0042.Trapping Rain Water/README_EN.md b/solution/0000-0099/0042.Trapping Rain Water/README_EN.md
index 791b1461a9def..c00c414234d3e 100644
--- a/solution/0000-0099/0042.Trapping Rain Water/README_EN.md	
+++ b/solution/0000-0099/0042.Trapping Rain Water/README_EN.md	
@@ -84,6 +84,36 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function trap(height: number[]): number {
+    let ans = 0;
+    let left = 0, right = height.length - 1;
+    let maxLeft = 0, maxRight = 0;
+    while (left < right) {
+        if (height[left] < height[right]) {
+            // move left
+            if (height[left] >= maxLeft) {
+                maxLeft = height[left];
+            } else {
+                ans += (maxLeft - height[left]);
+            }
+            ++left;
+        } else {
+            // move right
+            if (height[right] >= maxRight) {
+                maxRight = height[right];
+            } else {
+                ans += (maxRight - height[right]);
+            }
+            --right;
+        }
+    }
+    return ans;
+};
+```
+
 ### **C++**
 
 ```cpp
diff --git a/solution/0000-0099/0042.Trapping Rain Water/Solution.ts b/solution/0000-0099/0042.Trapping Rain Water/Solution.ts
new file mode 100644
index 0000000000000..5cc965adafc9d
--- /dev/null
+++ b/solution/0000-0099/0042.Trapping Rain Water/Solution.ts	
@@ -0,0 +1,25 @@
+function trap(height: number[]): number {
+    let ans = 0;
+    let left = 0, right = height.length - 1;
+    let maxLeft = 0, maxRight = 0;
+    while (left < right) {
+        if (height[left] < height[right]) {
+            // move left
+            if (height[left] >= maxLeft) {
+                maxLeft = height[left];
+            } else {
+                ans += (maxLeft - height[left]);
+            }
+            ++left;
+        } else {
+            // move right
+            if (height[right] >= maxRight) {
+                maxRight = height[right];
+            } else {
+                ans += (maxRight - height[right]);
+            }
+            --right;
+        }
+    }
+    return ans;
+};
\ No newline at end of file