Array - 1 Solutions

Problem_1_Product_Except_Self.java

@@ -0,0 +1,26 @@
+class Solution {
+    public int[] productExceptSelf(int[] nums) {
+        //[1,2,3,4]
+        //left pass - [1,1,2,6]
+        //right pass -[24,12,4,1]
+        //result - [24,12,8,6]
+
+        int rp = 1;
+        int n = nums.length;
+        int result[] = new int[n];
+        result[0] = 1;
+
+        //forward pass...
+        for(int i = 1 ; i < n ; i++) {
+            rp = rp * nums[i-1];
+            result[i] = rp;
+        }
+        //backward pass...
+        rp  = 1;
+        for(int i = n-2 ; i >= 0 ; i-- ) {
+            rp = rp * nums[i+1];
+            result[i] = rp * result[i];
+        }
+        return result;
+    }
+}

Problem_2_Diagonal_traverse.java

@@ -0,0 +1,39 @@
+class Solution {
+    public int[] findDiagonalOrder(int[][] mat) {
+        int r = 0; int c = 0;
+        int m = mat.length;
+        int n = mat[0].length;
+        int[] result = new int[m*n];
+        boolean flag = true;
+        for(int i = 0 ; i < result.length ; i++) {
+            result[i] = mat[r][c];
+            if(flag) {
+                if(r == 0 && c != n-1) {
+                    c++;
+                    flag = false;
+                }
+                else if(c == n-1) {
+                    r++;
+                    flag = false;
+                }
+                else {
+                    r--; c++;
+                }
+            }
+            else {
+                if(c == 0 && r != m-1) {
+                    r++;
+                    flag = true;
+                }
+                else if(r == m-1) {
+                    c++;
+                    flag = true;
+                }
+                else {
+                    c--; r++;
+                }
+            }
+        }
+        return result;
+    }
+}

Problem_3_Matrix_elements_spiral_order.java

@@ -0,0 +1,35 @@
+class Solution {
+    public List<Integer> spiralOrder(int[][] matrix) {
+        int m = matrix.length;
+        int n = matrix[0].length;
+        int top = 0 ; int bottom = m-1; int right = n-1; int left = 0;
+        List<Integer> l = new ArrayList<>();
+        while(left <= right && top <= bottom) {
+            if(left <= right && top <= bottom) {
+                for(int j = left; j <= right; j++) {
+                    l.add(matrix[top][j]);
+                }
+            }
+            top++;
+            if(left <= right && top <= bottom) {
+                for(int i = top; i <= bottom; i++) {
+                    l.add(matrix[i][right]);
+                }
+            }
+            right--;
+            if(left <= right && top <= bottom) {
+                for(int j = right; j >= left; j--) {
+                    l.add(matrix[bottom][j]);
+                }
+            }
+            bottom--;
+            if(left <= right && top <= bottom) {
+                for(int i = bottom; i >= top; i--) {
+                    l.add(matrix[i][left]);
+                }
+            }
+            left++;
+        }
+        return l;
+    }
+}