Weekly Contest 129, 130

Author: MaskRay

best-sightseeing-pair.cc

@@ -0,0 +1,13 @@
+// Best Sightseeing Pair
+class Solution {
+public:
+  int maxScoreSightseeingPair(vector<int>& A) {
+    int i = 0, l = 0, r = 0;
+    for (int x: A) {
+      r = max(r, l+x-i);
+      l = max(l, x+i);
+      i++;
+    }
+    return r;
+  }
+};

binary-prefix-divisible-by-5.cc

@@ -0,0 +1,13 @@
+// Binary Prefix Divisible By 5
+class Solution {
+public:
+  vector<bool> prefixesDivBy5(vector<int>& A) {
+    vector<bool> r;
+    int s = 0;
+    for (int x: A) {
+      s = (s*2+x)%5;
+      r.push_back(!s);
+    }
+    return r;
+  }
+};

binary-string-with-substrings-representing-1-to-n.cc

@@ -0,0 +1,16 @@
+// Binary String With Substrings Representing 1 To N
+class Solution {
+public:
+  bool queryString(string S, int N) {
+    if (S.size()*2 < N) return false;
+    for (; N; N--) {
+      string a;
+      for (int i = N; i; i /= 2)
+        a += '0'+i%2;
+      reverse(a.begin(), a.end());
+      if (S.find(a) == string::npos)
+        return false;
+    }
+    return true;
+  }
+};

convert-to-base-2.cc

@@ -0,0 +1,10 @@
+// Convert to Base -2
+class Solution {
+public:
+  string baseNeg2(int N) {
+    string s;
+    while (s += "01"[N&1], N = (N-(N&1))/-2);
+    reverse(s.begin(), s.end());
+    return s;
+  }
+};

next-greater-node-in-linked-list.cc

@@ -0,0 +1,15 @@
+// Next Greater Node In Linked List
+class Solution {
+public:
+  vector<int> nextLargerNodes(ListNode* h) {
+    vector<int> a, s, r;
+    for (int i = 0; h; h = h->next, i++) {
+      a.push_back(h->val);
+      r.push_back(0);
+      for (; s.size() && a[s.back()] < a[i]; s.pop_back())
+        r[s.back()] = a[i];
+      s.push_back(i);
+    }
+    return r;
+  }
+};

number-of-enclaves.cc

@@ -0,0 +1,28 @@
+// Number of Enclaves
+#define FOR(i, a, b) for (remove_cv<remove_reference<decltype(b)>::type>::type i = (a); i < (b); i++)
+#define REP(i, n) FOR(i, 0, n)
+
+class Solution {
+public:
+  int numEnclaves(vector<vector<int>>& A) {
+    int m = A.size(), n = A[0].size(), one = 0, x, y;
+    vector<pair<int, int>> q;
+    REP(i, m)
+      REP(j, n)
+        if (A[i][j]) {
+          one++;
+          if (!i || !j || i==m-1 || j==n-1) {
+            A[i][j] = 0;
+            q.emplace_back(i, j);
+          }
+        }
+    REP(i, q.size()) {
+      tie(x, y) = q[i];
+      if (x && !--A[x-1][y]) q.emplace_back(x-1, y);
+      if (x+1<m && !--A[x+1][y]) q.emplace_back(x+1, y);
+      if (y && !--A[x][y-1]) q.emplace_back(x, y-1);
+      if (y+1<n && !--A[x][y+1]) q.emplace_back(x, y+1);
+    }
+    return one - q.size();
+  }
+};

partition-array-into-three-parts-with-equal-sum.cc

@@ -0,0 +1,11 @@
+// Partition Array Into Three Parts With Equal Sum
+class Solution {
+public:
+  bool canThreePartsEqualSum(vector<int>& A) {
+    int e = accumulate(A.begin(), A.end(), 0)/3, s = 0, c = 0;
+    for (int x: A)
+      if ((s += x) == e)
+        s = 0, c++;
+    return c >= 3;
+  }
+};

smallest-integer-divisible-by-k.cc

@@ -0,0 +1,11 @@
+// Smallest Integer Divisible by K
+class Solution {
+public:
+  int smallestRepunitDivByK(int K) {
+    int s = 0;
+    for (int i = 0; i < K; i++)
+      if (!(s = (s*10+1)%K))
+        return i+1;
+    return -1;
+  }
+};