3152-special-array-ii.cc

leetcode/cpp/3152-special-array-ii.cc

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+// https://leetcode.com/problems/special-array-ii/
+
+class Solution {
+public:
+    vector<bool> isArraySpecial(vector<int>& nums, vector<vector<int>>& queries) {
+        size_t n = nums.size();
+        // prefix[i] stores how many pairs have same parity with nums[k+1]
+        // for num[k] with k in [0, i)
+        vector<int> prefix(n, 0);
+        for (size_t i = 1; i < n; ++i) {
+            int prev = nums[i-1], cur = nums[i];
+            prefix[i] = prefix[i-1] + ((cur & 1) == (prev & 1));
+        }
+
+        vector<bool> ans;
+        ans.reserve(queries.size());
+        for (const auto& v: queries) {
+            ans.push_back(prefix[v[1]] - prefix[v[0]] == 0);
+        }
+        return ans;
+    }
+};