feat(LeetCode): add solutions

LeetCode/longest-common-prefix.ts

@@ -0,0 +1,9 @@
+function longestCommonPrefix(strs: string[]): string {
+  for (let i = 0; i < strs[0].length; i++) {
+    for (let s of strs) {
+      if (s[i] !== strs[0][i]) return s.slice(0, i);
+    }
+  }
+
+  return strs[0];
+}

LeetCode/missing-number.ts

@@ -0,0 +1,10 @@
+function missingNumber(nums: number[]): number {
+  let n = nums.length;
+  let total = (n * (n + 1)) / 2;
+  let sum = nums.reduce((a, b) => a + b);
+
+  return total - sum;
+}
+
+console.log(missingNumber([0, 2, 3])); // 1
+console.log(missingNumber([3, 0, 1])); // 2

LeetCode/successful-pairs-of-spells-and-potions.ts

@@ -0,0 +1,26 @@
+function successfulPairs(
+  spells: number[],
+  potions: number[],
+  success: number
+): number[] {
+  let ans: number[] = [];
+
+  potions.sort((a, b) => a - b);
+
+  for (let spell of spells) {
+    let left = 0;
+    let right = potions.length;
+
+    while (left < right) {
+      let mid = Math.floor(left + (right - left) / 2);
+      if (potions[mid] * spell < success) {
+        left = mid + 1;
+      } else {
+        right = mid;
+      }
+    }
+    ans.push(potions.length - left);
+  }
+
+  return ans;
+}