Improvement

Signed-off-by: Leo Ma <[email protected]>

Author: begeekmyfriend

084_largest_rectangle_in_histogram/rect_in_histogram.c

@@ -3,22 +3,34 @@
 
 static int largestRectangleArea(int* heights, int heightsSize)
 {
-    int i, max_area = 0;
+    int *indexes = malloc(heightsSize * sizeof(int));
+    int *left = malloc(heightsSize * sizeof(int));
+    int *right = malloc(heightsSize * sizeof(int));
+
+    int i, pos = 0;
     for (i = 0; i < heightsSize; i++) {
-        if (i > 0 && heights[i - 1] == heights[i]) {
-            continue;
-        }
-        int low = i;
-        int high = i;
-        while (low - 1 >= 0 && heights[low - 1] >= heights[i]) {
-            low--;
+        while (pos > 0 && heights[indexes[pos - 1]] >= heights[i]) {
+            pos--;
         }
-        while (high + 1 < heightsSize && heights[high + 1] >= heights[i]) {
-            high++;
+        left[i] = pos == 0 ? -1 : indexes[pos - 1];
+        indexes[pos++] = i;
+    }
+
+    pos = 0;
+    for (i = heightsSize - 1; i >= 0; i--) {
+        while (pos > 0 && heights[indexes[pos - 1]] >= heights[i]) {
+            pos--;
         }
-        int area = (high - low + 1) * heights[i];
+        right[i] = pos == 0 ? heightsSize : indexes[pos - 1];
+        indexes[pos++] = i;
+    }
+
+    int max_area = 0;
+    for (i = 0; i < heightsSize; i++) {
+        int area = heights[i] * (right[i] - left[i] - 1);
         max_area = area > max_area ? area : max_area;
     }
+
     return max_area;
 }
 

169_majority_element/majority.c

@@ -3,9 +3,8 @@
 
 static int majorityElement(int* nums, int numsSize)
 {
-    int i, count = 1;
-    int major = nums[0];
-    for (i = 1; i < numsSize; i++) {
+    int i, major, count = 0;
+    for (i = 0; i < numsSize; i++) {
         if (count == 0) {
             major = nums[i];
             count++;
@@ -15,7 +14,6 @@ static int majorityElement(int* nums, int numsSize)
             count--;
         }
     }
-
     return major;
 }