100题之数组中超过出现次数超过一半的数字以及超过三分之一的两个数字，超过四分之一的三个数字

//============================================================================ // Name : 100题之数组中出现次数超过一半的数字.cpp // Author : // Version : // Copyright : Your copyright notice // Description : Hello World in C++, Ansi-style //============================================================================ #include <iostream> using namespace std; const int MAX=65535; void MoreThanForthNum(int *a,int length,int &first,int &second,int &thrid) { if(!a||length<=0) throw new string("no valid input"); if(length<=2) throw new string("no valid input"); if(length==3) { first=a[0]; second=a[1]; thrid=a[2]; return ; } first=0; second=0; thrid=0; int symbol=a[0],number=1; int symbol1=0,number1=0; int symbol2=0,number2=0; for(int i=1;i<length;i++) { if(!number&&symbol1!=a[i]&&symbol2!=a[i]) { symbol=a[i]; number=1; } else if(symbol==a[i]) number++; else if(symbol1!=a[i]&&symbol2!=a[i]) { number--; } if(!number1&&symbol!=a[i]&&symbol2!=a[i]) { symbol1=a[i]; number1=1; } else if(symbol1==a[i]) number1++; else if(symbol!=a[i]&&symbol2!=a[i]) number1--; if(!number2&&symbol!=a[i]&&symbol1!=a[i]) { symbol2=a[i]; number2=1; } else if(symbol2==a[i]) number2++; else if(symbol!=a[i]&&symbol1!=a[i]) number2--; } first=symbol; second=symbol1; thrid=symbol2; number1=0; number=0; number2=0; for(int i=0;i<length;i++) { if(a[i]==first) number++; if(a[i]==second) number1++; if(a[i]==thrid) number2++; } if(!(number*4>=length&&number1*4>=length&&number2*4>=length)) throw new string("invalid input"); } bool MoreThanThridNum(int *a,int length,int &first,int &second) { if(!a||length<=0) throw new string("no valid input"); if(length==1) throw new string("no valid input"); if(length==2) { first=a[0]; second=a[1]; return true; } int symbol=a[0],number=1; int symbol1=MAX,number1=0; for(int i=1;i<length;i++) { if(!number&&symbol1!=a[i]) { symbol=a[i]; number=1; } else if(symbol==a[i]) number++; else { number--; } if(!number1&&symbol!=a[i]) { symbol1=a[i]; number1=1; } else if(!number1&&symbol==a[i]) { symbol1=MAX; continue; } else if(symbol1==a[i]) number1++; else if(symbol1!=MAX) number1--; } first=symbol; second=symbol1; } int MoreThanHalfNum(int *a,int length) { if(!a||length<=0) throw new string("no valid input"); int symbol=a[0]; int number=1; for(int i=1;i<length;i++) { if(symbol==a[i]) number++; else number--; if(number==0) { symbol=a[i]; number=1; } } number=0; for(int i=0;i<length;i++) { if(symbol==a[i]) number++; } if(number*2>=length) return symbol; else throw new string("no valid input"); } int main() { //int a[10]={2,2,3,3,2,2,3}; int a[] = {5, 5, 5, 7, 7, 8, 8, 8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 5, 5, 5, 6, 5, 6, 7, 7, 7, 7, 7, 7, 7, 7, 5, 7, 2, 2, 2, 5, 5, 5, 8}; int length=40; // cout << MoreThanHalfNum(a,length)<< endl; int first,second,thrid; // MoreThanThridNum(a, length,first,second); // cout<<first<<" "<<second<<endl; MoreThanForthNum(a, length,first,second,thrid); cout<<first<<" "<<second<<" "<<thrid<<endl; return 0; }