DFS 1 completed

01-matrix.cpp

@@ -0,0 +1,61 @@
+class Solution {
+public:
+    vector<vector<int>> updateMatrix(vector<vector<int>>& mat) {
+        queue<pair<int, int>> zeroes;
+        int n = mat.size();
+        int m = mat[0].size();
+
+        vector<vector<int>> dist(n, vector<int>(m,INT_MAX));
+        unordered_set<string> us;
+
+        for (int i=0;i<mat.size();i++) {
+            for (int j=0;j<mat[0].size();j++) {
+                if (mat[i][j] == 0) {
+                    zeroes.push({i,j});
+                    dist[i][j] = 0;
+                }
+            }
+        }
+
+        auto getKeys = [](int x, int y) -> string {
+            return to_string(x) + "," + to_string(y);
+        };
+
+        auto visited = [&](int x, int y) {
+            string key = getKeys(x, y);
+            if (us.find(key) == us.end()) {
+                us.insert(key);
+                return true;
+            }
+            return false;
+        };
+
+        auto isSafe = [&](int newX, int newY){
+            if (newX >=0 && newY >=0 && newX < mat.size() && newY < mat[0].size()) {
+                return true;
+            }
+            return false;
+        };
+
+        auto addAdjacent = [&](pair<int, int> p) -> void {
+            vector<vector<int>> dirs = {{1,0}, {-1,0} ,{0, 1} , {0, -1}};
+            for (int i=0;i<dirs.size();i++) {
+                int newX = p.first + dirs[i][0];
+                int newY = p.second + dirs[i][1];
+                if (isSafe(newX, newY) && dist[newX][newY] > dist[p.first][p.second] + 1 && visited(newX, newY)) {
+                    zeroes.push({newX, newY});
+                    dist[newX][newY] = dist[p.first][p.second] + 1;
+                }
+            }
+        };
+
+        while (!zeroes.empty()) {
+            pair<int, int> p = zeroes.front();
+            zeroes.pop();
+
+            addAdjacent(p);
+        }
+
+        return dist;
+    }
+};

floodFill.cpp

@@ -0,0 +1,58 @@
+class Solution {
+public:
+    vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int color) {
+        queue<pair<int, int>> q;
+        unordered_set<string> visited;
+        int original = image[sr][sc];
+
+        q.push({sr, sc});
+
+        auto getKey = [&](int x, int y){
+            return to_string(x) + "," + to_string(y);
+        };
+
+        visited.insert(getKey(sr, sc));
+
+
+        auto isSafe = [&](int x, int y) -> bool {
+            if (x >= 0 && y >=0 && x < image.size() && y < image[0].size()) {
+                return true;
+            }
+            return false;
+        };
+
+        auto isVisited = [&](pair<int, int> cell) -> bool {
+            string key = getKey(cell.first, cell.second);
+
+            if (visited.find(key) == visited.end()) {
+                visited.insert(key);
+            } else {
+                return false;
+            }
+            return true;
+        };
+
+        auto addAdjacentCells = [&](pair<int, int> cell) -> void {
+            vector<vector<int>> dirs = {{0,1}, {0,-1}, {1, 0}, {-1,0}};
+            for (int i=0;i<dirs.size();i++) {
+                int newX = cell.first + dirs[i][0];
+                int newY = cell.second + dirs[i][1];
+                if  (isSafe(newX, newY) && isVisited({newX, newY})) {
+                    q.push({newX, newY});
+                }
+            }
+        };
+
+        while (!q.empty()) {
+            auto cell = q.front();
+            q.pop();
+
+            if (image[cell.first][cell.second] == original) {
+                image[cell.first][cell.second] = color;
+                addAdjacentCells(cell);
+            }
+        }
+
+        return image;
+    }
+};