题目：

题解：

int evalRPN(char** tokens, int tokensSize) {
    int n = tokensSize;
    int stk[(n + 1) / 2];
    memset(stk, 0, sizeof(stk));
    int index = -1;
    for (int i = 0; i < n; i++) {
        char* token = tokens[i];
        if (strlen(token) > 1 || isdigit(token[0])) {
            index++;
            stk[index] = atoi(token);
        } else {
            switch (token[0]) {
                case '+':
                    index--;
                    stk[index] += stk[index + 1];
                    break;
                case '-':
                    index--;
                    stk[index] -= stk[index + 1];
                    break;
                case '*':
                    index--;
                    stk[index] *= stk[index + 1];
                    break;
                case '/':
                    index--;
                    stk[index] /= stk[index + 1];
                    break;
            }
        }
    }
    return stk[index];
}