summary-ranges.cc & majority-element-ii.cc

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 202/211 problems.
+Solved 204/213 problems.
 
 ## Database
 
@@ -12,6 +12,8 @@ See [database.md](database.md)
 
 | # | Title | Solution |
 |---| ----- | -------- |
+|229|[Majority Element II](/problems/majority-element-ii/)|[majority-element-ii.cc](majority-element-ii.cc)|
+|228|[Summary Ranges](/problems/summary-ranges/)|[summary-ranges.cc](summary-ranges.cc)|
 |227|[Basic Calculator II](/problems/basic-calculator-ii/)|[basic-calculator-ii.cc](basic-calculator-ii.cc)|
 |226|[Invert Binary Tree](/problems/invert-binary-tree/)|[invert-binary-tree.cc](invert-binary-tree.cc)|
 |225|[Implement Stack using Queues](/problems/implement-stack-using-queues/)|[implement-stack-using-queues.cc](implement-stack-using-queues.cc)|

majority-element-ii.cc

@@ -0,0 +1,22 @@
+// Majority Element II
+class Solution {
+public:
+  vector<int> majorityElement(vector<int> &a) {
+    int y = 0, z = 1, cy = 0, cz = 0;
+    for (auto x: a) {
+      if (x == y) cy++;
+      else if (x == z) cz++;
+      else if (! cy) y = x, cy = 1;
+      else if (! cz) z = x, cz = 1;
+      else cy--, cz--;
+    }
+    cy = cz = 0;
+    for (auto x: a)
+      if (x == y) cy++;
+      else if (x == z) cz++;
+    vector<int> r;
+    if (cy > a.size()/3) r.push_back(y);
+    if (cz > a.size()/3) r.push_back(z);
+    return r;
+  }
+};

summary-ranges.cc

@@ -0,0 +1,18 @@
+// Summary Ranges
+#define FOR(i, a, b) for (int i = (a); i < (b); i++)
+#define REP(i, n) FOR(i, 0, n)
+
+class Solution {
+public:
+  vector<string> summaryRanges(vector<int> &a) {
+    vector<string> r;
+    int s = 0, n = (int)a.size();
+    REP(i, n) {
+      if (i == n-1 || a[i]+1 != a[i+1]) {
+        r.push_back(s == i ? to_string(a[i]) : to_string(a[s])+"->"+to_string(a[i]));
+        s = i+1;
+      }
+    }
+    return r;
+  }
+};