微软面试题 -- 在排序数组中，找出给定数字的出现次数
在排序数组中，找出给定数字的出现次数，比如 [1, 2, 2, 2, 3] 中2的出现次数是3次。
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网上一位仁兄写了如下解法：
int cnt(int a[], int v, int n){ int mid, b = 0, e = n-1; int low, high; while(b < e - 1) { mid = b + (e-b)/2; if(a[mid] >= v) e = mid; else b = mid; } if(a[b] == v) low = b; else if(a[e] == v) low = e; else return 0; b = 0; e = n-1; while(b < e -1) { mid = b +(e-b)/2; if(a[mid] <= v) b = mid; else e = mid; } if (a[e] == v) high = e; else if(a[b] == v) high = b; else return 0; return high - low + 1; }