View Code of Problem 1009

#include <cstdio>
#include <cstring>
int dp[105][10005];
int n,m,c=1;
int out(int y,int x){
    return y<0 || (y>x*(x-1)/2) || (y>0&&y<x-1);
}
int test(int x,int y){
    int i;
    if(out(y,x))
        return 0;
    if(!y)
        return 1;
    if(dp[x][y] != -1)
        return dp[x][y];
    for(i = 1;i<=x;i++){
        dp[x][y] = test(x-i, y-i*(x-i));
        if(dp[x][y])
            return 1;
    }
    return 0;
}
int main(){
    memset(dp, -1, sizeof(dp));
    while(scanf("%d %d",&n,&m) && (n+m)){
        printf("Case %d: %d ",c++,n);
        if(test(n,m))
            printf("lines with exactly %d crossings can cut the plane into %d pieces at most.\n",m,n+m+1);
        else
            printf("lines cannot make exactly %d crossings.\n",m);
    }
    return 0;
}