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| package algorithm;
public class TrappingRainWater {
// 凹形槽的两个条件：一个是往右找，比自己高的，那就停止；一个是找最近接自己高度的
// 也就是第二高的，记录位置
public static int trap(int[] height) {
int left = 0;
int right = 1;
int area = 0;
while (right < height.length && left < right) {
if (height[left] < height[right]) {
left++;
right = left + 1;
continue;
}
int tempMax = right;
while (right < height.length && height[left] > height[right]) {
if (height[right] > height[tempMax]) {
tempMax = right;
}
right++;
}
if (right < height.length && height[right] > height[tempMax]) {
tempMax = right;
}
int minHeight = Math.min(height[left], height[tempMax]);
for (int i = left + 1; i < tempMax; i++) {
area += minHeight - height[i];
}
left = tempMax;
right = left + 1;
}
return area;
}
public static int trap1(int[] height) {
int left = 0;
int right = height.length - 1;
int leftMax = 0;
int rightMax = 0;
int ans = 0;
while (left < right) {
if (height[left] < height[right]) {
if (height[left] >= leftMax) {
leftMax = height[left];
} else {
ans += leftMax - height[left];
}
left++;
} else {
if (height[right] >= rightMax) {
rightMax = height[right];
} else {
ans += rightMax - height[right];
}
right
}
}
return ans;
}
public static void main(String[] args) {
int[] height = new int[]{0,1,0,2,1,0,1,3,2,1,2,1};
System.out.println(trap1(height));
height = new int[]{4,2,0,3,2,5};
System.out.println(trap1(height));
height = new int[]{4,2,3};
System.out.println(trap1(height));
}
}
|
