Merge pull request larissalages#119 from PriyanshVerma/master

add N Queens (51.cpp)

Author: larissalages

leetcode/cpp/backtracking/51.cpp

@@ -0,0 +1,52 @@
+#define f first
+#define s second
+class Solution {
+private:
+	int n;
+	vector<string> board;
+	vector<vector<string>> res;
+	
+	void solve(int row) {
+		if (row == n) {
+			res.push_back(board);
+			return;
+		}
+
+		for (int col = 0; col < n; ++col)
+		{
+			board[row][col] = 'Q';
+			if (valid(row, col)) {
+				solve(row+1);
+			} 
+			board[row][col] = '.';
+		}
+	}
+
+	bool valid(int ROW, int COL) {
+		vector<pair<int,int>> dirs = 
+                    {{-1,-1}, {-1,0}, {-1,1},
+									   {0, -1}, 		     {0,1},
+									   {1, -1}, {1, 0}, {1,1}};
+		for (auto d: dirs) {
+			int k = 1;
+			int nr = ROW + k*d.f, nc = COL + k*d.s;
+			while (nr < n && nc < n && nr >= 0 && nc >= 0) {
+				if (board[nr][nc] == 'Q')
+					return false;
+				k++;
+				nr = ROW + k*d.f;
+				nc = COL + k*d.s;
+			}
+		}
+
+		return true;
+	}
+
+public:
+	vector<vector<string>> solveNQueens(int n) {
+		this->n = n;
+		this->board = vector<string> (n, string (n, '.'));
+		solve(0);
+		return res;
+	}
+};

leetcode/cpp/string/567.cpp

@@ -0,0 +1,32 @@
+class Solution {
+public:
+    bool checkInclusion(string sml, string lrg) {
+        if (lrg.length() < sml.length())
+            return false;
+        
+        unordered_map<char, int> targetMap, haveMap;
+        for(char c: sml) {
+            targetMap[c]++;
+        }
+        
+        for(char c: lrg.substr(0, sml.length())) {
+            haveMap[c]++;
+        }
+        
+        int st=0, en=sml.length()-1;
+        while(en < lrg.length()) {
+            if (targetMap == haveMap) {
+                return true;
+            }
+            
+            haveMap[lrg[st]]--; 
+            if (haveMap[lrg[st]]==0) haveMap.erase(lrg[st]);
+            st++;
+            en++; 
+            if (en<lrg.length())
+                haveMap[lrg[en]]++;
+        }
+        return false;
+        
+    } 
+};