feat: leetcode contest 299

Author: upupming

leetcode/contest-299/2322. Minimum Score After Removals on a Tree.js

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+/**
+ * @param {number[]} nums
+ * @param {number[][]} edges
+ * @return {number}
+ */
+const minimumScore = function (nums, edges) {
+  const n = nums.length
+  const e = Array(n).fill(0).map(() => [])
+  for (const [x, y] of edges) {
+    e[x].push(y)
+    e[y].push(x)
+  }
+  let xAll = 0; let xBC, xA; let ret = 1e10
+  for (const a of nums) xAll ^= a
+  for (let i = 0; i < n; i++) {
+    for (const j of e[i]) {
+      // 删除边 i-j, j 所在的子树作为单调的一块
+      // 计算以 i 为根，不含 j 的子树的异或和
+      xBC = dfs(i, -1, j)
+      xA = xAll ^ xBC
+      // 在 B 中枚举第二条被删除的边
+      dfs2(i, -1, j)
+    }
+  }
+  return ret
+
+  function dfs (x, fa, ban) {
+    let ans = nums[x]
+    for (const y of e[x]) {
+      if (y !== fa && y !== ban) ans ^= dfs(y, x, ban)
+    }
+    return ans
+  }
+  function dfs2 (x, fa, ban) {
+    let ans = nums[x]
+    for (const y of e[x]) {
+      if (y !== fa && y !== ban) {
+        const xC = dfs2(y, x, ban)
+        ans ^= xC
+        const xB = xBC ^ xC
+        ret = Math.min(ret, Math.max(xA, xB, xC) - Math.min(xA, xB, xC))
+      }
+    }
+    return ans
+  }
+}

leetcode/contest-299/5229. Maximum Score Of Spliced Array.js

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+/**
+ * @param {number[]} nums1
+ * @param {number[]} nums2
+ * @return {number}
+ */
+ var maximumsSplicedArray = function(a1, a2) {
+  function solve(a1, a2) {
+      const n = a1.length, d = [], dp = []
+      dp[-1] = 0
+      let max = -1e10, sum = 0
+      for (let i = 0; i < n; i++) {
+          d[i] = a2[i] - a1[i]
+          sum += a1[i]
+          dp[i] = Math.max(dp[i-1], 0) + d[i]
+          max = Math.max(max, dp[i])
+      }
+      if (max > 0) sum += max
+      return sum
+  }
+
+  return Math.max(solve(a1, a2), solve(a2, a1))
+};

leetcode/contest-299/6100. Count Number of Ways to Place Houses.js

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+/**
+ * @param {number} n
+ * @return {number}
+ */
+ var countHousePlacements = function(n) {
+  const dp = [], P = 1e9 + 7
+  dp[0] = [1, 0]
+  for (let i = 1; i <= n; i++) {
+      dp[i] = []
+      // i 处不放房子
+      dp[i][0] = (dp[i-1][0] + dp[i-1][1]) % P
+      // i 处放房子
+      dp[i][1] = dp[i-1][0] % P
+  }
+  const x = BigInt((dp[n][0] + dp[n][1]) % P)
+  return (x * x) % BigInt(P)
+};

leetcode/contest-299/6101. Check if Matrix Is X-Matrix.js

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+/**
+ * @param {number[][]} grid
+ * @return {boolean}
+ */
+ var checkXMatrix = function(g) {
+  const n = g.length
+  let ok = true
+  for (let i = 0; i < n; i++) {
+      for (let j = 0; j < n; j++) {
+          if (i === j || (i+j) === n-1) {
+              if (g[i][j] === 0) ok = false
+          } else {
+              if (g[i][j] !== 0) ok = false
+          }
+      }
+  }
+  return ok
+};