add int statistic functions
add int statistic functions

Yexiaoxing/CUHKSZLib,cuhkshenzhen/CUHKSZLib,alesiong/CUHKSZLib,cuhkshenzhen/CUHKSZLib,Yexiaoxing/CUHKSZLib,cuhkshenzhen/CUHKSZLib,alesiong/CUHKSZLib,alesiong/CUHKSZLib,Yexiaoxing/CUHKSZLib