找出已排序陣列中的最長平臺。平臺是連續的一串值相同的元素，如1,2,2,3中[1], [2, 2], [3]都是平臺。

方案一：常規思路，利用STL的map容器統計每個元素的出現頻數，然後從map容器中選出頻數最大的元素。

/* * Function: longest_plateau_v1 *---------------------------------------------------------------------- * Find the longest plateau of an integer array using STL map container. */ void longest_plateau_v1( int x[], int n, int * e, int * len ) { map<int, int> plateau; for( int i = 0; i < n; ++i ) ++plateau[x[i]]; map<int, int>::const_iterator iter; *len = 0; for( iter = plateau.begin(); iter != plateau.end(); ++iter ) { if( iter->second > *len ) { *e = iter->first; *len = iter->second; } } }

思路二：只對陣列掃描一遍，且不利用輔助結構（陣列或map結構）來統計元素頻數。

/* * Function: longest_plateau *-------------------------------------------------------- * Find the longest plateau of an integer array. * A better version, only one round of scanning is needed. */ void longest_plateau_v2( int x[], int n, int *e, int *idx, int * max_len ) { *max_len = 1; *e = x[0]; *idx = 0; int len = 1; for( int i = 1; i < n; ++i ) { if( x[i] == x[i - 1] ) { ++len; } else { if( *max_len < len ) { *max_len = len; *e = x[i - 1]; *idx = i - len; } len = 1; } } if( len > *max_len ) { *max_len = len; *e = x[n-1]; *idx = n - len; } }

測試程式：

int main(int argc, _TCHAR* argv[]) { int x[] = { 1, 2, 2, 2, 3, 3, 4, 4, 4, 5, 5, 5, 5, 5 }; int e = 0; int max_len = 0; int idx = -1; longest_plateau_v2( x, 14, &e, &idx, &max_len ); cout << "The longest plateau is: " << e << endl; cout << "Length = " << max_len << endl; cout << "Index = " << idx << endl; return 0; }

各位朋友若有更好的思路，歡迎補充，謝謝！