传送门
A - A+...+B Problem
题意：n个数最大值a，最小值b，求和的可能数量。
#include<cstdio> #include<algorithm> using namespace std; int read_p,read_ca; inline int read(){ read_p=0;read_ca=getchar(); while(read_ca<'0'||read_ca>'9') read_ca=getchar(); while(read_ca>='0'&&read_ca<='9') read_p=read_p*10+read_ca-48,read_ca=getchar(); return read_p; } int n,a,b; int main(){ n=read();a=read();b=read(); if (n==1){ printf("%d\n",a==b); return 0; } if (a>b) puts("0");else printf("%lld\n",1LL*(b-a)*(n-2)+1); }