单峰向量定义为A[0, n),其中前缀{a0, a1, …, ak}严格递增,后缀{ak+1, ak+2, …, an-1}严格递减。 设计算法在O(logn)的时间内找到最大值所在位置k。
int find (int arr[],int len){
if (len ==1) {
return 0;
}
if (arr[0]<arr[1]) {
return 0;
}
int low = 0,high = len -1;
if(arr[high ]> arr[high - 1]){
return high;
}
int mid = 0;
while (low<high) {
mid = (low+high)/2;
if (arr[mid]>=arr[mid -1]&&arr[mid] > arr[mid+1]) {
return mid;
}
if (arr[mid] > arr[mid+1]) {
high = mid -1;
}
if (arr[mid] > arr[mid-1]) {
low = mid + 1;
}
}
return mid;
}