Contains Duplicate III & Maximal Square

Author: MaskRay

README.md

@@ -2,7 +2,7 @@
 
 [LeetCode solutions](http://maskray.me/blog/2014-06-29-leetcode-solutions) gives some thoughts on selected problems.
 
-Solved 194/203 problems.
+Solved 196/205 problems.
 
 ## Database
 
@@ -12,6 +12,8 @@ See [database.md](database.md)
 
 | # | Title | Solution |
 |---| ----- | -------- |
+|221|[Maximal Square](https://leetcode.com/problems/maximal-square/)|[maximal-square.cc](maximal-square.cc)|
+|220|[Contains Duplicate III](https://leetcode.com/problems/contains-duplicate-iii/)|[contains-duplicate-iii.cc](contains-duplicate-iii.cc)|
 |219|[Contains Duplicate II](https://leetcode.com/problems/contains-duplicate-ii/)|[contains-duplicate-ii.cc](contains-duplicate-ii.cc)|
 |218|[The Skyline Problem](https://leetcode.com/problems/the-skyline-problem/)|[the-skyline-problem.cc](the-skyline-problem.cc)|
 |217|[Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)|[contains-duplicate.cc](contains-duplicate.cc)|

contains-duplicate-iii.cc

@@ -0,0 +1,18 @@
+// Contains Duplicate III
+class Solution {
+public:
+  bool containsNearbyAlmostDuplicate(vector<int> &a, int k, int t) {
+    typedef long long ll;
+    if (k < 1 || t < 0) return false;
+    unordered_map<ll, ll> b;
+    for (vector<int>::size_type i = 0; i < a.size(); i++) {
+      ll x = a[i], j = (x-INT_MIN)/(t+1LL);
+      if (b.count(j) || b.count(j-1) && x-b[j-1] <= t || b.count(j+1) && b[j+1]-x <= t)
+        return true;
+      if (i >= k)
+        b.erase((ll(a[i-k])-INT_MIN)/(t+1LL));
+      b[j] = x;
+    }
+    return false;
+  }
+};

maximal-rectangle.cc

@@ -10,20 +10,26 @@ class Solution {
   int maximalRectangle(vector<vector<char> > &a) {
     if (a.empty()) return 0;
     int m = a.size(), n = a[0].size(), ans = 0;
-    vector<int> h(n), l(n), r(n, n-1);
+    vector<int> h(n, 0), l(n, 0), r(n, n-1);
     REP(i, m) {
-      int ll = -1;
-      REP(j, n) {
-        h[j] = a[i][j] == '1' ? h[j]+1 : 0;
-        if (a[i][j] == '0') ll = j;
-        l[j] = h[j] ? max(h[j] == 1 ? 0 : l[j], ll+1) : j;
-      }
-      int rr = n;
-      ROF(j, 0, n) {
-        if (a[i][j] == '0') rr = j;
-        r[j] = h[j] ? min(h[j] == 1 ? n-1 : r[j], rr-1) : j;
-        ans = max(ans, (r[j]-l[j]+1)*h[j]);
-      }
+      int ll = 0, rr = n-1;
+      REP(j, n)
+        if (a[i][j] == '1')
+          l[j] = max(l[j], ll);
+        else {
+          l[j] = 0;
+          ll = j+1;
+        }
+      ROF(j, 0, n)
+        if (a[i][j] == '1') {
+          h[j]++;
+          r[j] = min(r[j], rr);
+          ans = max(ans, (r[j]-l[j]+1)*h[j]);
+        } else {
+          h[j] = 0;
+          r[j] = n-1;
+          rr = j-1;
+        }
     }
     return ans;
   }

maximal-square.cc

@@ -0,0 +1,22 @@
+// Maximal Square
+#define FOR(i, a, b) for (int i = (a); i < (b); i++)
+#define REP(i, n) for (int i = 0; i < (n); i++)
+
+class Solution {
+public:
+  int maximalSquare(vector<vector<char>> &a) {
+    if (a.empty()) return 0;
+    int m = a.size(), n = a[0].size(), ans = 0;
+    vector<int> s(n, 0);
+    REP(i, m) {
+      int ul = 0;
+      REP(j, n) {
+        int t = ul;
+        ul = s[j];
+        s[j] = a[i][j] == '1' ? min(min(t, s[j-1]), s[j])+1 : 0;
+        ans = max(ans, s[j]);
+      }
+    }
+    return ans*ans;
+  }
+};