题目如下:
Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.
For example,
Given [0,1,0,2,1,0,1,3,2,1,2,1]
, return 6
.
解析思路:先找到最高峰,然后从两边向中间计算,因为两边向中间是递增的趋势
参考代码如下:
int trap(int A[], int n) {
if(n <= 2) return 0;
int max = -1, maxInd = 0;
int i = 0;
for(; i < n; ++i){//先找出最高峰
if(A[i] > max){
max = A[i];
maxInd = i;
}
}
int area = 0, root = A[0];
for(i = 0; i < maxInd; ++i){//从左侧到最高峰的计算
if(root < A[i]) root = A[i];
else area += (root - A[i]);
}
for(i = n-1, root = A[n-1]; i > maxInd; --i){//从右侧到最高峰的计算
if(root < A[i]) root = A[i];
else area += (root - A[i]);
}
return area;
}