update: daily Apr12 champion

daily/Apr12.cpp

@@ -0,0 +1,51 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Solution {
+ public:
+  /**
+   * @brief LC2923: Find the Champion
+   * this solution time complexity is based on two layer of loops
+   * So, really slow
+   * @param grid
+   * @return int
+   */
+  int findChampion(vector<vector<int>>& grid) {
+    int sz = grid.size();
+    // int the bool matrix, if grid[i][j] == 1 && i != j, i win
+    unordered_map<int, int> mp;
+    using pair_type = decltype(mp)::value_type;
+    for (int i = 0; i < sz; i++) {
+      for (int j = 0; j < sz; j++) {
+        if (i == j) {
+          // nothing
+        }
+        if (grid[i][j] == 1) {
+          mp[i]++;
+          mp[j]--;
+        } else {
+          mp[i]--;
+          mp[j]++;
+        }
+      }
+    }
+    auto best = std::max_element(
+        mp.begin(), mp.end(), [](const pair_type& lhs, const pair_type& rhs) {
+          return lhs.second < rhs.second;
+        });
+    return best->first;
+  }
+
+  /// @brief Every time we update the result, this is fast
+  /// @param grid
+  /// @return
+  int findChampionOP(vector<vector<int>>& grid) {
+    int ans = 0;
+    for (int i = 1; i < grid.size(); i++) {
+      if (grid[i][ans]) {
+        ans = i;
+      }
+    }
+    return ans;
+  }
+};