Array1

Problem1.java

@@ -0,0 +1,24 @@
+class Problem1 {
+    public int[] productExceptSelf(int[] nums) {
+        int n = nums.length;
+
+        int[] result = new int[n];
+
+        int rp = 1;
+        result[0] = 1;
+
+        for(int i=1; i<n; i++){ // left pass
+            rp = rp * nums[i-1];
+            result[i] = rp;
+        }
+
+        rp = 1;
+
+        for(int i=n-2; i>=0; i--){ // right pass
+            rp = rp*nums[i+1];
+            result[i] = result[i] * rp;
+        }
+
+        return result;
+    }
+}

Problem2.java

@@ -0,0 +1,43 @@
+class Problem2 {
+    public int[] findDiagonalOrder(int[][] mat) {
+        int m = mat.length;
+        int n = mat[0].length;
+
+        int[] result = new int[m*n];
+        int r = 0, c = 0;
+
+        boolean dir = true;
+
+        for(int i = 0; i < m * n; i++) {
+            result[i] = mat[r][c];
+
+            if(dir) {
+                if(c == n - 1) {
+                    r++;
+                    dir = false;
+                }
+                else if(r == 0) {
+                    c++;
+                    dir = false;
+                }
+                else {
+                    r--; c++;
+                }
+            } else {
+                if(r == m - 1) {
+                    c++;
+                    dir = true;
+                }
+                else if(c == 0) {
+                    r++;
+                    dir = true;
+                }
+                else {
+                    r++; c--;
+                }
+            }
+        }
+
+        return result;
+    }
+}

Problem3.java

@@ -0,0 +1,41 @@
+class Problem3 {
+    public List<Integer> spiralOrder(int[][] matrix) {
+        int m = matrix.length;
+        int n = matrix[0].length;
+
+        int top = 0, bottom = m-1, left = 0, right = n-1;
+
+        List<Integer> result = new ArrayList<>();
+
+        while(top <= bottom && left <= right){
+
+            for(int i=left; i<=right; i++){
+                result.add(matrix[top][i]);
+            }
+            top++;
+
+            for(int i=top; i<=bottom; i++){
+                result.add(matrix[i][right]);
+            }
+            right--;
+
+            if(top <= bottom)
+            {
+                for(int i=right; i>=left; i--){
+                    result.add(matrix[bottom][i]);
+                }
+                bottom--;
+            }
+
+            if(left <= right)
+            {
+                for(int i=bottom; i>=top; i--){
+                    result.add(matrix[i][left]);
+                }
+                left++;
+            }
+        }
+
+        return result;
+    }
+}