feat(LeetCode): add solutions

LeetCode/find-the-index-of-the-first-occurrence-in-a-string.ts

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+function strStr(haystack: string, needle: string): number {
+  return haystack.indexOf(needle);
+}

LeetCode/longest-continuous-increasing-subsequence.ts

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+// https://leetcode.com/problems/longest-continuous-increasing-subsequence/solutions/3359434/javascript-typescript-solution/
+
+function findLengthOfLCIS(nums: number[]): number {
+  let cur = 1;
+  let ans = 1;
+
+  for (let i = 1; i < nums.length; i++) {
+    // if (nums[i] > nums[i - 1]) {
+    //   cur += 1
+    //   ans = Math.max(cur, ans)
+    // } else {
+    //   cur = 1;
+    // }
+
+    // same above. using ternary operator
+    cur = nums[i] > nums[i - 1] ? cur + 1 : 1;
+    ans = Math.max(cur, ans);
+  }
+
+  return ans;
+}
+
+// cur=1, ans=1
+
+// [1,3,5,4,7] 3 > 1
+//  0 1 2 3 4  < i=1
+
+// cur=2, ans=2
+
+// [1,3,5,4,7] 5 > 3
+//  0 1 2 3 4  < i=2
+
+// cur=3, ans=3
+
+// [1,3,5,4,7] 4 > 5
+//  0 1 2 3 4  < i=3
+
+// cur=1, ans=3
+
+// [1,3,5,4,7] 7 > 4
+//  0 1 2 3 4  < i=4
+
+// cur=2, ans=3
+
+// using DP
+function findLengthOfLCIS2(nums: number[]): number {
+  const dp = new Array(nums.length).fill(1);
+
+  for (let i = 1; i < nums.length; i++) {
+    if (nums[i] > nums[i - 1]) {
+      dp[i] = dp[i - 1] + 1;
+    }
+  }
+
+  return Math.max(...dp);
+}

LeetCode/robot-return-to-origin.ts

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+function judgeCircle(moves: string): boolean {
+  let x = 0;
+  let y = 0;
+
+  for (let move of moves) {
+    if (move === 'R') x++;
+    if (move === 'L') x--;
+    if (move === 'U') y++;
+    if (move === 'D') y--;
+  }
+
+  return x === 0 && y === 0;
+}