1-3+5-7+.....-99+101
=(1-3)+(5-7)+.....(97-99)+101
#includeint main(){int s=101-100/4*2; printf("%d\n",s); return 0;}或:#includeint main(){int i,s=101; for(i=3;i<100;i+=4) s-=2; printf("%d\n",s); return 0;}