Added 1 solution & modified 1 solution

varunu28 · varunu28 · commit c4ad4c493ce2 · 2020-10-10T07:52:09.000-07:00
diff --git a/Easy/Reverse String.java b/Easy/Reverse String.java
@@ -4,10 +4,8 @@ public void reverseString(char[] s) {
     int end = s.length - 1;
     while (start < end) {
       char temp = s[start];
-      s[start] = s[end];
-      s[end] = temp;
-      start++;
-      end--;
+      s[start++] = s[end];
+      s[end--] = temp;
     }
   }
 }
diff --git a/Medium/Count Submatrices With All Ones.java b/Medium/Count Submatrices With All Ones.java
@@ -0,0 +1,27 @@
+class Solution {
+  public int numSubmat(int[][] mat) {
+    int m = mat.length;
+    int n = mat[0].length;
+    int res = 0;
+    for (int i = 0; i < m; i++) {
+      int[] arr = new int[n];
+      Arrays.fill(arr, 1);
+      for (int j = i; j < m; j++) {
+        for (int k = 0; k < n; k++) {
+          arr[k] &= mat[j][k];
+        }
+        res += countOneRow(arr);
+      }
+    }
+    return res;
+  }
+  
+  private int countOneRow(int[] A) {
+    int res = 0, length = 0;
+    for (int i = 0; i < A.length; ++i) {
+      length = (A[i] == 0 ? 0 : length + 1);
+      res += length;
+    }
+    return res;
+  }
+}

Original file line number	Diff line number	Diff line change
`@@ -4,10 +4,8 @@ public void reverseString(char[] s) {`
`4`	`4`	`int end = s.length - 1;`
`5`	`5`	`while (start < end) {`
`6`	`6`	`char temp = s[start];`
`7`		`- s[start] = s[end];`
`8`		`- s[end] = temp;`
`9`		`- start++;`
`10`		`- end--;`
	`7`	`+ s[start++] = s[end];`
	`8`	`+ s[end--] = temp;`
`11`	`9`	`}`
`12`	`10`	`}`
`13`	`11`	`}`